Table of Content

10 January 2023, Volume 31 Issue 1

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Invited Column: Wearable and Intelligent Textiles

Research progress of electronic fabrics in the intelligent wearable field

YIN Yunlei, GUO Cheng, YANG Hongying, LI Hong, WANG Zheng

2023, 31(1):  1-12.  DOI: 10.19398/j.att.202207026

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With the development of human society and the progress of science and technology, intelligent wearable devices have attracted more and more attention. Among various types of smart wearable devices, electronic fabrics that combine fabrics with electronics are expected to play an essential role in health monitoring, motion monitoring, intelligent medical treatment, and human-computer interaction.
At present, the application of intelligent wearable devices is becoming increasingly critical in People's daily life. Intelligent wearable devices are gradually developing towards flexibility and miniaturization to meet the characteristics of flexibility, lightweight, and effortless skin fitting. Textiles are one of the ideal choices for intelligent wearables because of their excellent flexibility, lightweight, and air permeability.
Fabric sensors have excellent flexibility, air permeability, human body fit, and other characteristics and can be easily integrated with clothing. They have been widely used in sports monitoring, health monitoring, and intelligent medical treatment. In addition, fiber-shaped light-emitting electronic devices can be seamlessly integrated with textiles, allowing textile display, sensing, and camouflage applications. Moreover, luminous electronic fabrics play a vital role in transportation, security, anti-counterfeiting, clothing, and aviation. As the application of intelligent wearable electronic devices continues to expand, in order to ensure the sustainable operation of smart wearable electronic devices, it is essential to develop reliable, intelligent wearable power systems and energy management devices.
Flexibility and comfort based on fabric are essential for intelligent wearable devices. Electronic fabrics can inherit the advantages of light weight, flexibility, air permeability, and a certain degree of ductility of traditional fabrics while having electronic functions. Currently, fabric electronic devices have been widely studied and used in sensing, luminescence, energy conversion, and energy storage. With further development, electronic fabrics may be combined with a variety of smart wearable devices in the future, bringing us a more intelligent life.
As a new type of intelligent textile, electronic fabrics have excellent potential in the intelligent wearable field. In the future, electronic fabrics with unique structures and various functions are expected to be integrated into people's lives, which can not only meet the needs of daily wear but also serve the emerging fields of personalized health monitoring, motion monitoring, intelligent medical treatment, and human-computer interaction. Although electronic fabrics have made significant achievements in intelligent wearables, the performance, large-scale manufacturing, and unified technical testing standards of electronic fabrics are still the challenges facing the research and application of electronic fabrics in the field of intelligent wearables. Therefore, it is necessary to improve other electronic fabrics' design, function, and performance, so as to accelerate the further development of electronic fabrics in the field of intelligent wearables.

Preparation and reliability of wearable electric heating elements

ZHANG Huirong, XIA Zhaopeng, CHEN Hao, PAN Jiajun, WANG Tao, LIU Xiaochen

2023, 31(1):  13-27.  DOI: 10.19398/j.att.202208029

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Wearable electric heating elements with high heating efficiency, adjustable heating temperature and long heating time are the key components of electric heating garments, and are widely used in personal heating, sports training and local heat therapy. In recent years, the industrialization of wearable electric heating elements has been accelerated because the preparation and performance of wearable electric heating elements with different materials have been researched in-depth. Such reliability problems as nontoxicity, breathability, flexibility, weight, safety temperature and lifecycle of wearable electric heating elements is commonly ignored.
The wearable electric heating elements including metal materials, carbon materials, conductive polymers and MXene can be classified into one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) wearable electric heating elements. The 1D wearable electric heating elements can be prepared by multiple methods such as preparing metal wires directly with metal materials, composite heating lines, yarns with coating metal particles,and wet spinning with conductive materials. Although the 1D wearable electric heating elements have excellent spinning performance, the overall resistance can be changed because of fabric tightness, density of warp and weft, content of conductive yarn and the fabric strain. The preparation methods of 2D wearable electric heating elements include coating, soaking, chemical deposition and printing, and the heating performance of elements is related to the thickness and uniformity of the conductive layer. The 3D wearable electric heating elements can be prepared by two methods, including building the aerogel structure with the conductive layer obtained by depositing and building the aerogel structure directly with conductive materials. Although the favourable thermal insulation effect is shown in the 3D wearable electric heating elements, the overall resistance is significantly affected by the produced strain when the element is stressed. Metal 1D wearable electric heating elements and carbon nanotube 2D wearable electric heating elements are commonly used in industrial production. According to the modified conductive materials, the preparation of wearable electric heating elements with electromagnetic shielding, human infrared radiation and sensing is becoming a current research hotspot. However, it is easily overlooked that after the conductive materials are treated with different processes, the chemical residues in the elements may be harmful to human health.
The safety voltage of human body is 36 V, and the minimum temperature for low-temperature scald which is caused by direct contact of human skin with heat source is 45 ℃. The scald risk is increased because the pain nerve response becomes dull in the hot and humid environment. Therefore, it is important to limit the applied voltage and maximum temperature of the elements and to ensure the breathability and comfortability of the elements. The excessive heating temperature is caused by uneven resistance distribution or unreasonable design of wearable electric heating elements, and the heating temperature shock is caused by the poor washability and wear-resisting property. The wearable electric heating elements are encapsulated by polymer in order to improve the washability and wear-resisting property, which has a series of negative effects on the elements, such as reduced flexibility, poor breathability and increased weight.
Wearable electric heating elements have become one of the important ways to regulate human thermal comfort. Although increasingly in-depth research has been carried out on electric heating materials, the reliability of the prepared wearable electric heating elements still needs to be improved. Therefore, it is still a difficult point in this field to meet the requirements of safety and washability of components, as well as flexibility, air permeability and lightness. The industrialization of wearable electric heating elements can be accelerated by the in-depth research on the encapsulation process.

Research progress on energy supply of wearable devices

LIANG Jiawen, LI Tingting, YAN Zhanlin, ZHANG Bin, CAO Chongyang, FU Zhifang, CHEN Naichao

2023, 31(1):  28-39.  DOI: 10.19398/j.att.202207028

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With the rapid development of artificial intelligence and Internet of Things technology, smart wearable technology has gradually matured and been widely used, and the demand for the sustainability and independence of smart wearable device energy supply in various industries is getting higher and higher. The limited design space of wearable devices is not conducive to the expansion of energy storage devices, and redundant power supplies will inevitably bring electronic waste and environmental damage. Therefore, the need to develop technologies that directly obtain energy from human physiology and the external environment so as to strengthen the independence of energy supply is becoming increasingly urgent.
Currently, energy such as solar energy, ambient thermal energy, electromagnetic energy, and mechanical energy is harvested by micro-energy harvesting technology from the surrounding environment. Co-generator technology supplies energy to wearable electronic devices, and provides energy to energy supply equipment by converting micro energy in the external environment into electrical energy, such as friction generators, thermoelectric generators, mechanical and piezoelectric generators and solar cells. At the same time, the development of wearable technology is inseparable from the synergy with energy storage technology. Second, since micro-energy harvesting and energy storage require corresponding control and regulation circuits, it is necessary to develop system-level energy management strategies to improve their efficiency, reliability and practicality in wearable systems.
With the development of energy supply technology, self-powered sensors can provide power to sensing devices. To enable implantable and sustainable wearable electronics, self-powered sensor technology integrates self-powering and sensing, solving the drawback that most current sensors cannot work independently and must rely on an external power supply. Using new micro-energy harvesting or energy storage or both, sensing devices can continuously collect more operational data in harsh environments and build powerful data analysis libraries.
Technical research based on micro-energy harvesting and energy storage technology is an important foundation for the energy supply of wearable devices. In the future, researchers can collect more other clean energy and store it. While the diversity of energy supply technologies is expanded, the energy utilization efficiency is greatly increased. This offers great potential for energy supply for wearable devices.
Flexible and small-scale energy-integrated devices have greatly promoted the innovative research of energy supply technology in wearable devices. So far, miniaturized devices, high-power efficient conversion, energy storage enhancement and other technologies have greatly promoted the application of wearable devices in industries such as inspection. In the future, a large number of wearable device energy supply operation data can be obtained, the operation law of the equipment can be more deeply grasped, and combined with intelligent algorithm analysis, a more intelligent, reliable, convenient and energy-saving wearable continuous energy supply device can be designed.

Application progress on PEDOT:PSS in flexible wearable solar cells

LÜ Dongfang, CAO Yimin, SONG Lixin, XIONG Jie

2023, 31(1):  40-53.  DOI: 10.19398/j.att.202204037

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Poly(3,4-ethylenedioxythiophene): polystyrene sulfonic acid (PEDOT:PSS) which is a kind of conductive polymer with superior electrical conductivity and excellent flexibility, has great potential in the field of wearable solar cells. At present, more and more people are focusing on the application research of flexible solar cells in wearability, so as to solve a series of problems about flexible solar cells, including flexibility, specific power, portability and compatibility. PEDOT:PSS, as electrode and hole transport layer, plays an important role in the research of different flexible solar cells, which promotes the rapid development of flexible solar cells.
As an electrode, PEDOT:PSS plays a different role in DSSCs, OSCs, PSCs, and the modification methods are also slightly different. In DSSCs, PEDOT:PSS has high room temperature conductivity and remarkable stability, which can catalyze the I^3-/I^- redox reaction in solar cells. In terms of performance improvement, doping-based research ideas have been formed. The preparation process is simple, non-toxic, environmentally friendly and involve excellent electrocatalytic activity. In OSCs, the emergence of PEDOT:PSS can replace the traditionally expensive ITO, and the non-conductive component PSS in the polymer can be removed by solvent post-treatment and other methods, which significantly improves the conductivity of the PEDOT:PSS electrode. In PSCs, PEDOT:PSS can be used as a transparent substrate electrode and a top electrode of flexible PSCs, respectively. After further modification of PEDOT:PSS by doping or post-treatment, the conductivity of PEDOT:PSS as a conventional electrode is further improved, and its optical transmittance is further enhanced as a top electrode, which enables the performance of the battery device to ensure a high energy conversion efficiency. In terms of flexibility, compared with the traditional battery devices constructed by metal electrodes or ITO electrodes, the devices constructed by modified PEDOT:PSS can still maintain a level comparable to the initial efficiency after bending for hundreds of times, which provides a new idea for the development of efficient and stable flexible optoelectronic devices.
As a hole transport layer, PEDOT:PSS is only used in OSCs and PSCs due to the different structures of solar cells. In OSCs, PEDOT:PSS has a wide range of advantages as a hole transport layer. Its solution processing characteristics make it suitable for large-scale production, and it has excellent performance in smoothing electrode interface and extracting holes. Post-treatment or doping is often used to solve the problem that the strong acidity of PEDOT:PSS leads to the low efficiency of the battery. On the one hand, the acidity of PEDOT:PSS is reduced, and on the other hand, the electrochemical and optical properties of PEDOT:PSS can be improved, thus greatly improving the efficiency of OSCs. In PSCs, PEDOT:PSS is widely used as hole transport layer materials due to its matching energy level with perovskite and suitable conductivity, and simple preparation at low temperature. After doping-based modification, the energy level between PEDOT:PSS and perovskite is more matched, the carrier mobility and hole extraction ability are improved, and the efficiency of PSCs is significantly improved. Through the optimization of the preparation process, the stability and mechanical flexibility are also well balanced, which makes flexible wearable PSCs possible.
For flexible wearable solar cells, there are two primary problems: how to prepare high-efficiency and high-flexibility battery devices, and how to improve the stability of the battery while maintaining high efficiency and high flexibility. The application of PEDOT:PSS as electrode and hole transport layer in different flexible solar cells is becoming increasingly extensive. Researchers have continuously improved and optimized the electrode materials of flexible solar cells by such methods as doping, post-processing and so on. In these solutions, PEDOT:PSS has also made an irreplaceable contribution to the development of flexible solar cells, which is of far-reaching significance.

Preparation of the fabric electrode and its application in spacer fabric-based triboelectric nanogenerators

ZHOU Suibo, WANG Zheshan, HU Jianchen, ZHANG Keqin

2023, 31(1):  54-63.  DOI: 10.19398/j.att.202204060

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The integration of triboelectric nanogenerator (TENG) technology and traditional textiles has brought new vitality and more application directions for intelligent textiles, in which the fabric electrode provides a conductive layer for TENGs. In recent years, the studies of TENGs mainly focus on electrode materials, friction materials and structural design, while the studies on conductive layers in the related research fields of spacer fabric TENGs are relatively few. It is helpful for the application of spacer fabric-based TENGs to prepare spacer fabric TENGs by referring to the construction method of fabric electrodes in common fabric-based TENGs.
Apart from the basic function of converting mechanical energy into electrical energy, the spacer fabric-based TENGs can also be used as a self-powered sensor in many directions, such as human motion detection, foot pressure sensing and gas monitoring. At present, in addition to conducting yarn weaving and dipping conductive materials to construct fabric electrodes, a relatively stable conductive layer can be formed on the fabric through physical vapor deposition, chemical vapor deposition, electroplating or electrodeless plating to be applied to TENGs, which provides some examples for the construction of suitable fabric electrodes for spacer fabric-based TENGs. However, the existing fabric electrodes of spacer fabric-based TENGs are mainly woven by dipping or conductive yarn weaving machines. Although they can effectively give the fabric a certain conductivity and achieve mass production, their conductive layer stability is greatly limited.
The output of the fabric-based TENGs is still at a low level. The charge density on the surface of the friction layer is an important factor that determines the performance of all TENGs. However, the charge collection and transmission of the electrode layer only need to be conductive to ensure a certain output. Therefore, most researchers often neglect the influence of the fabric electrode layer on the output. There is a potential resistance range in the fabric electrode layer, even if the conductivity is improved, the total amount of saturated stored charges cannot be changed, and the micro conductive path structure of the fabric that transmits charges also directly affects the output performance, which provides a theoretical basis for spacer fabric-based TENGs to improve the output so as to facilitate their practical application.
Based on the study of the conductive layer and special spacer fabric structure of fabric-based TENGs, we summarize the preparation methods of fabric electrodes and their application in the spacer fabric-based TENG, and discuss the potential difficulties and severe challenges of fabric electrodes hindering its output. It hoped that this review can not only deepen the connection between smart textiles and TENGs to a certain extent, but also provide some references for the relevant research and application of wearable TENGs in the future.

Structure and properties of GNs/CNTs functional knitted fabrics

SONG Qianqian, SHAO Yiqin, CHEN Weilai

2023, 31(1):  64-72.  DOI: 10.19398/j.att.202203039

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With the rapid development of electronic intelligent devices, intelligent textiles formed by the combination of electronic device systems and textiles came into being. Electro-thermal fabrics are a kind of intelligent textiles which convert electric energy into thermal energy through electric heating elements. The common heating element materials have some disadvantages, such as poor flexibility, limited heating temperature range and high power consumption. Among electro-thermal materials, the graphene nanosheets (GNs) and carbon nanotubes (CNTs) with excellent electrical properties enhance their thermal properties. For instance, the heat dissipation speed is fast, the ambient temperature is greatly increased, and the electrothermal conversion rate is nearly 100% with no luminous loss. Besides, the probability of power decay in the long-term use process is low, and the heating power is stable. Wearable sensors need to contact the human body directly or indirectly like existing textile fabrics, and the deformation range of human joints in daily activities is usually 3%-55%, which requires satisfactory elongation and deformability of the sensor. At present, most of the research on conductive heating fabrics is based on woven fabrics. On the contrary, the research on knitted structure with good flexibility is not deep enough. Knitted fabrics have high elasticity, high flexibility and recoverability because of its unique coil structure. They can achieve both high sensitivity and large deformation.
Polyester knitted fabrics with the three different structures of weft plain weave, mesh weave and spacer weave were selected and GNs/CNTs functional knitted fabrics were prepared by the safe and simple spraying method. The surface morphology structure and mechanical properties of the fabrics were characterized by the Zeiss polarizing microscope, SEM and FTIR. The electrical properties and tensile strain sensing properties of the fabrics were compared and analyzed by using the electronic fabric strength meter and the two-probe digital multimeter, and the electro-thermal properties of the fabrics under different applied voltage modes were studied systematically by infrared thermal imager. The results show that GNs/CNTs uniformly adheres to the surface of the fiber and yarn in the state of intertwining and interlocking without forming a film on the surface of the fabric, and the fabric structure is clearly visible; GNs/CNTs functional knitted fabrics exhibit improved mechanical properties and satisfactory electrical properties and the electrical conductivity of the GNs/CNTs mesh fabric reaches 1,567 S/cm; at low voltages, GNs/CNTs compound knitted fabrics exhibit certain electro-thermal properties, which is related to the structure of fabrics. To be specific, weft plain knitted fabrics have the fastest heating rate and highest heating efficiency, and mesh fabrics can be heated to 116.3 ℃ at 10 V. Compared with the weft plain knitted fabric with a highest heating rate of 15.3 ℃/s, the temperature rising and cooling rates of the mesh and spacer fabrics are relatively low. At the same power, the average heating efficiency of the weft plain knitted fabric can reach 210.5 ℃/W, which is higher than that of the mesh fabric and spacer fabric.
The preparation method of GNs/CNTs functional knitted fabrics is simple and effective and the knitted fabrics with different structures can meet the multi-scene applications in intelligent clothing, health care and other fields. The research results can provide references and suggestions for the design and development of intelligent textiles.

Research progress of ERPs technology in fabric tactile comfort evaluation

ZHAI Shuna, YUAN Jie, LOU Lin

2023, 31(1):  73-81.  DOI: 10.19398/j.att.202203070

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People's health design requirements for the fit, functionality and comfort of wearable fabrics are gradually increasing, and the research on the perceptual mechanism of fabric tactile comfort is urgent. The event-related potentials (ERPs) technology with microsecond time resolution can quickly capture the changes of EEG signals related to fabric comfort, which is of great significance for exploring the dynamic perception mechanism of fabric comfort.
ERPs technology can effectively monitor the relevant brain regions under the fabric contact stimulation in real time, so as to obtain the potential components related to the tactile comfort of the fabric. By recording the amplitude, latency and distribution of evoked potential components, we can quickly, objectively and accurately understand the psychological and physiological changes in the process of stimulation, so as to characterize the comfort level of human body. Specifically, the evoked potential components P50, P100, P200, P300 and N450 are characterization indexes of brain physiological response to mild tactile stimulation and contact pressure stimulation. In the process of application of ERPs technology, it is mainly affected by physical, physiological and psychological aspects. Physical factors include stimulation probability, stimulation frequency, stimulation mode, stimulation task difficulty and stimulus characteristics; physiological factors include age, gender, health status, sensory selection and stimulation site; psychological factors include subjects' emotional state and attention.
At present, the evaluation of tactile comfort of fabrics based on ERPs technology has become a hot research topic. The amplitude and latency of its components can effectively evaluate the tactile comfort perception of fabrics, which provides great potential for in situ characterization of tactile stimuli of fabrics.
Based on the brain perceptual representation principle of ERPs technology, we summarize the research status of ERPs technology in the evaluation of the fabric′s slight tactile comfort and contact pressure comfort. It is concluded that the components P50, P100, P200, and P300 are related to the fabric's slight tactile comfort perception, and N450 is related to fabric deep contact pressure perception. Many factors such as physics, human physiology and psychology affect ERPs evoked potentials. In the process of fabric contact stimulation, it is very important to master the quantitative influence of interference factors on brain evoked potentials, and to control and eliminate interference factors. It is very important to explore the characterization of fabric comfort by using ERPs technology in the future. We should further explore the brain potential components induced by surface property stimulation such as cold and warm feeling, clinginess and itching feeling and cross-sensory stimulation, and quantitatively study the stimulus and potential components of fabrics.

Application progress of embroidery technology in smart textiles

FENG Yuan, ZHOU Jinli, YANG Hongying, WANG Zheng, XIONG Fan, DU Lixin

2023, 31(1):  82-91.  DOI: 10.19398/j.att.202204021

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Embroidery is a method of decoration on the surface of finished fabrics, which has a certain aesthetic value. As one of the most commonly used development technologies in the field of smart textiles, embroidery technology has great application value in smart textiles because of its excellent personalized customization function, process reproducibility and production efficiency. In recent years, with its unique processing advantages, embroidery technology has provided increasingly extensive research and development ideas for wearable devices, flexible electronic fabrics and other products, so it has been widely studied and applied in signal identification and transmission, biosensor and physical sensing.
At present, with the gradual expansion of the smart wearable field in the market, flexible fabrics already have the functions of signal recognition and signal transmission. Compared with most fabric processing technologies, embroidery technology is remarkable in Tailored Fiber Placemen (TFP) function, which gives it an advantage in the preparation of flexible electronic tags and signal transmission lines. In terms of biosensors, embroidery technology has been one of the main methods to prepare fabric ECG electrodes and EMG electrodes. Users only need to wear smart textiles with integrated biosensors, and the sensors will be located in the corresponding monitoring position. The use of embroidery instead of weaving or knitting can make the design and shape of the electrode more personalized, so that it can adapt to different applications and monitoring scenes. Therefore, embroidery technology has high application potential in the field of intelligent wearable to monitor human bioelectric signals. Textile sensors can provide the evaluation of general parameters such as pressure, stress, temperature and humidity, and have great application value in structural monitoring and medical and health care. At present, many scholars at home and abroad have made good physical sensors such as stress sensor, temperature sensor and pressure sensor through embroidery technology. Embroidery has other important applications in the field of smart textiles, such as physiotherapy textiles and temperature-adjusted textiles.
Intelligent textiles are a new product in the interdisciplinary research field. In addition to transmission and sensing functions, smart textiles have the structural characteristics of being multiple, multi-dimensional and multi-scale, but also show the characteristics of light weight, low modulus and skin affinity. With its unique processing advantages, embroidery technology provides more extensive research and development ideas for wearable devices, flexible electronic fabrics and other products, so it is used in intelligent textile research in various fields.
At present, the application of embroidery technology in smart textiles has great potential, not only with powerful personalized customization and convenient fabric surface beautification and decoration, but also with good process reproducibility and structural dimensional stability, which can ensure the rapid prototyping of designed products and promote the quantitative production of new intelligent textiles. However, there are still some problems in the application of embroidery technology in smart textiles, such as the undiversified supply of conductive embroidery thread, insufficient applicability of printing software to intelligent textile design, and so on. The most important thing is to promote cooperation among embroidery and medicine, electronics, communications, materials, textiles and other disciplines, and constantly enhance and improve the functionality and practicability of the products. For this reason, it is necessary to strengthen the research and development of conductive yarns for embroidery, to study embroidery printing software and embroidery devices suitable for the design of intelligent textiles, and to promote cross-cooperation between embroidery technology and other fields.

Research progress of passive temperature-regulated clothing materials for personal thermal management

HAN Mengyao, REN Song, GE Can, FANG Jian

2023, 31(1):  92-103.  DOI: 10.19398/j.att.202205055

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Textiles play a vital role in human daily activities and social development. With the development of intelligent technology and the growing demand for clothing functionality, textiles with various new intelligent functions, such as temperature control, sensor monitoring and color change intelligence are favored by people. In order to reduce the energy consumption caused by space cooling, people hope that textiles can create a comfortable microclimate to regulate the temperature. Since temperature regulating textiles can effectively regulate the human body temperature and wear thermal and wet comfort based on the human body temperature regulation mechanism, they have been widely studied and developed in recent years. This energy-saving and diversified personal temperature regulation technology is called "personal thermal management" technology.
At present, textiles with personal thermal management performance can be divided into active temperature regulating textiles and passive temperature regulating textiles according to the energy source. Temperature regulating textiles can cool down or keep warm when connected to an external power source, which is "active". On the contrary, temperature regulating textiles can only rely on the characteristics of materials without additional energy, which is "passive".
The active cooling system refers to the system that uses gas or liquid as the cooling source. Under the condition of external power (such as electricity), the cooling source flows to absorb human heat to achieve the purpose of cooling. There are various liquid (gas) medium embedded cooling systems. Similarly, as for the active heating system, the heating source is driven by an external power source to keep warm, with the heating methods including electric heating, solar heating, chemical energy heating, and phase change material heating. Passive cooling system means that no additional energy is required for temperature regulation. The passive cooling methods mainly include reflection (radiation) cooling, infrared transparent cooling, phase change material cooling, etc., while passive heating methods include reflection (radiation) heating, reducing heat conduction, light heat conversion, etc. We mainly introduce passive thermal insulation clothing materials such as new clothing thermal insulation materials, reflective (radiation) materials, far-infrared emission materials and photo thermal conversion materials, passive cooling clothing materials such as conductive cooling materials, phase change cooling materials, reflective cooling materials, mid infrared high transmission (emission) radiation cooling materials, and double-sided temperature regulating clothing.
There are many kinds of passive temperature regulating clothing. Among various clothing materials, new temperature regulating clothing materials can achieve different radiant heat controls by changing the emissivity, reflectivity and transmissivity of the clothing, so as to regulate the clothing microclimate to achieve "all-weather" thermal comfort without consuming additional energy, that is, personal radiant heat management. Radiation cooling, radiation heat preservation and double-sided temperature regulating clothing materials have also become the focus of current research.
Advanced passive temperature regulating textiles rely on the heat transfer characteristics of the system and the structural design of the material. They do not need any external energy input to regulate the microclimate between the human body and the external environment, regulate the human body temperature, and maintain the thermal balance and thermal moisture comfort of the human body. In recent years, scholars at home and abroad have studied passive temperature regulating clothing materials from the aspects of temperature regulating materials, temperature regulating mechanism, clothing structure design, etc., and successfully applied the research results to the market. However, the development of passive temperature regulating clothing materials at this stage still faces many challenges, such as clothing responsiveness and durability, wearing safety and ecological health issues, and lack of implementation standards and comfort evaluation. In general, passive temperature regulating textiles have huge application potential and development space in the field of maintaining human thermal comfort. Therefore, the research on intelligent temperature regulating textiles still needs to be further deepened in order to create new intelligent textiles more quickly.

Fiber Materials

Rheological properties of cationic dyeable polyester

HUANG Zheng, SUN Yanlin, XIAO Shunli, LIN Xueyan, BAO Jianna, ZHANG Xianming, CHEN Wenxing

2023, 31(1):  104-112.  DOI: 10.19398/j.att.202203075

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Polyethylene terephthalate (PET) has low production cost, excellent mechanical properties, high thermal stability and excellent corrosion resistance. The polyester fiber formed by its processing is one of the world's largest synthetic fiber varieties, which is widely used in the field of textiles. The symmetrical molecular structure of PET and the absence of chemically active sites in the molecular chain lead to its easy crystallization and high crystallinity, poor hygroscopicity, and difficulty in dyeing. Therefore, the dyeing modification of PET to meet the demand for new textile products is in line with the development of the textile industry. Cationic dyeable polyester (CDP) fiber is the earliest successful development and currently the largest industrial production of modified species among the dyeing modifications of PET. However, in the actual production process, the introduction of sodium-5-sulfo-bis-(hydroxyethyl)-isophthalate (SIPE) makes the coking more severe in the pipeline, reflecting that the macroscopic flow behavior of the melt changes significantly after the introduction of SIPE.
In order to explore the changes of rheological properties of CDP melt, we analyzed the shear viscosity and non-Newtonian index of PET and CDP with similar intrinsic viscosities at the same die diameter capillary rheometer and rotational rheometer tests. On this basis, the viscous flow activation energy and structural viscosity index of the melt were obtained by analytical calculations. The variation of melt viscosity at different die diameters has also been studied. Subsequently, frequency scans and time scans were performed to investigate the trend of CDP melt viscosity with time. It is found that the ionic aggregation effect of strong polar sulfonic acid groups will form ionic aggregates which will increase the physical cross-linked structure inside the CDP melt, resulting in a significantly higher viscosity and structural viscosity index than the PET melt under similar characteristic viscosity. The formation and depolymerization of ionic aggregates are affected by temperature and shear, which makes CDP melts more sensitive to changes in temperature and shear rate than PET melts; the more relaxed the melt molecular chain is under large diameter, the lower the viscous flow activation energy and the non-Newtonian index is closer to 1; the heat generated by viscous dissipation of the melt increases at small diameter and the shear viscosity decreases; the melt viscosity of CDP tends to increase with the increase of heating time.
In the actual CDP production process, the change of melt viscosity will have a large impact on the production, and the appropriate melt temperature, conveying flow rate and extrusion rate should be selected with the analysis of rheological properties. The results of this study are conducive to analyzing the essential causes of coking caused by pipeline blockage due to viscosity changes during the pipeline transport of melt and finding the solution.

Study on L-lactide/meso-lactide copolymerization and its properties

ZHENG Wen, ZHANG Jiangang, LIU Xiong, GONG Lei, CHEN Shichang, BAO Jianna, ZHANG Xianming, CHEN Wenxing

2023, 31(1):  113-122.  DOI: 10.19398/j.att.202203074

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Polylactic acid (PLA), as a biodegradable material, can replace the current non degradable plastics and greatly reduce the environmental pollution caused by plastics. In addition, PLA has good thermal processability, biocompatibility and degradability, and will not pollute the environment after use. It can replace many traditional petroleum-based plastics, and has a wide range of applications. Generally, high-quality PLA is mainly prepared through stereoisomeric and specific ring opening polymerization of high-purity L-lactide or D-lactide. In the production process, L/D-lactide will be affected by factors such as catalyst, high temperature and reaction time, which will easily lead to a large amount of meso-lactide in the final product. The molecular weight, crystallinity, mechanical properties and thermal stability of PLA will be affected when meso-lactide enters the ring opening polymerization stage of L/D-lactide. Due to the similar properties of the three isomers and their characteristics of heat sensitivity, high freezing point and high boiling point, it is very difficult to purify L/D-lactide. This is an important factor affecting the quality and yield of lactide at present, and it is also a key and difficult point in the preparation process of lactide. It is of great significance to study the ring opening polymerization of meso-lactide and L-lactide obtained in actual industrial production and the product properties to guide the preparation process and application of PLA.
At present, research on the polymerization of L-lactide and meso-lactide focuses on the polymerization with L-lactide using high-purity meso-lactide as the monomer, and the properties are far from those of meso-lactide produced in the actual industrial production of L-lactide. Therefore, in this paper, the meso-lactide produced in the production process that is more in line with the industry is prepared by high-temperature heat treatment of L-lactide, and it is used as the polymerization monomer to explore the ring opening polymerization of L-lactide and meso-lactide, and to analyze the molecular weight, chemical structure, thermal performance and crystallization performance of the copolymer.
It is found that L-lactide could successfully undergo ring opening polymerization to obtain PLA copolymer with 0-5.0% meso-lactide, and the presence of meso-lactide does not significantly affect the molecular weight distribution uniformity of the polymer. With the increase of the content of meso-lactide, the molecular chain regularity of the copolymer decreases, and the crystallization region has a significant repulsion effect on the stereoisomers, resulting in the decrease of the crystallization rate and crystallization ability of the copolymer. Besides, the thermal performance parameters such as the thermal decomposition temperature, glass transition temperature, melting point and melting enthalpy of the copolymer are significantly reduced. Compared with PLA, the copolymer shows slower crystallization kinetics and the optimum crystallization temperature is about 100 ℃, which is consistent with PLA. The addition of meso-lactide will reduce the degree of ordering of copolymer macromolecular chain, but will not change the crystal structure of PLA.

Effects of densification methods on glycolysis and transesterification products of waste polyester textiles

LIU Zhiyang, GUAN Jun , GU Riqiang , LÜ Weiyang , WANG Xiuhua , YAO Yuyuan

2023, 31(1):  123-129.  DOI: 10.19398/j.att.202207048

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Polyester fiber, with excellent elasticity, wrinkle resistance and shape conformal property, is widely used in textile clothing, industrial packaging and other fields. As the amount of polyester fiber increases, the accumulation of waste polyester textiles also rises year by year, resulting in serious environmental pollution and resource waste problems. Waste polyester is depolymerized by chemical solvents to monomer as an effective raw material for the synthesis of high value-added recycled polyester materials, which is an effective way to achieve high-value recycling of the waste polyester textiles. Among the chemical methods, the glycolysis method not only has the advantages of mild reaction conditions and simple process, but also the ester exchange reaction between the alcoholysis product BHET and methanol can produce regenerated DMT comparable to primary petroleum-based materials, which is the most promising process route for the industrial preparation of the high-quality regenerated polyester materials. The densification methods of waste polyester textiles are a key factor affecting the efficiency and cost of the reaction during polyester alcoholysis and transesterification. However, most of the current glycolysis methods focus on the development of new and efficient depolymerization catalysts, and little research has been reported on the effect of different densification retreatment processes of raw materials on the alcoholysis products and the downstream regenerated DMT thereof.
In order to find the most suitable dense raw material for industrial decomposing poly waste polyester textile and preparation of regenerated DMT, the foaming, melt materials and melt extrusion materials derived from waste polyester textiles were prepared by the three densification methods of strong friction stirring, high temperature melting and screw heated extrusion, and depolymerized by ethylene glycol. Then, the alcoholysis products were futher transesterified by methanol to prepare the regenerative dimethyl terephthalate. The effect of different densification methods on the glycolysis and transesterification products of waste polyester textiles was investigated. The experimental results indicated that the maximum depolymerization rates of 99.2%, 99.02% and 98.2% and the yields of bis(2-hydroxyethyl) terephthalate (BHET) of 69.7%, 68.8% and 65.2%, respectively were achieved in 120 min for the foaming, melt, and melt extrusion materials under the same reaction conditions. The main components of the glycolysis products were BHET and its dimer, and the content of oligomers decreased with increase of depolymerization. Three glycolysis products were further transesterified with methanol under the same conditions to obtain DMT, and the DMT yields of 81.2%, 76.8% and 72.2% were achieved within 2.5 h for the foaming, melt, melt extrusion materials, respectively. Three transesterification products were purified by four times' methanol recrystallization and the DMT content was higher than 99%, which meets the requirements of the downstream high-performance recycled polyester products.
In order to improve the utilization rate of the reactor space, the reaction efficiency and product yield in the industrial production, it is an economical, efficient and feasible route to select the waste polyester with high specific surface area and relatively low densification as the raw material for the production of the regenerated DMT. The experimental results provide a useful reference for selecting suitable raw materials in the recycled polyester industry.

Preparation and properties of membranes based on PCL by electrospinning

ZHU Ranran, YUE Hongyin, CHEN Yonghui, LI Huijun

2023, 31(1):  130-135.  DOI: 10.19398/j.att.202205016

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Oil resources play an important role in social development, but there are also problems. For example, accidents in oil exploitation and transportation lead to a large number of oil spills in rivers, lakes and seas. If the oil pollution cannot be treated in time, it will cause serious harm to the ecological environment, waste of non renewable energy and loss of the national economy. Oil pollution treatment is not only a common problem facing the world, but also an urgent problem to be solved. The traditional methods for oil pollution treatment mainly include combustion method, fence collection method, chemical method, etc. However, it often leads to time consumption, high cost, poor effect, secondary pollution and other deficiencies. Therefore, how to efficiently and environmentally treat oil pollution is extremely important.
In order to better deal with various hazards caused by oil spill events, researchers have used electrospinning technology to prepare nanofiber membranes for oil treatment in recent years. Compared with traditional oil treatment methods, the fiber membrane prepared by electrospinning technology has small diameter, high specific surface area, small density, large porosity, high oil absorption efficiency and hydrophobic property. Therefore, in this paper, natural degradable polycaprolactone (PCL) was used as the raw material, PCL fiber membranes with different mass fractions were prepared by electrospinning method, and the surface morphology of the fibers was observed by scanning electron microscope. The water contact angle, oil absorption rate and oil retention rate of PCL fiber membranes with different mass fractions were tested and analyzed. The results showed that with the increase of PCL mass fraction, the fiber diameter gradually increased. When the PCL mass fraction was 16%, there was no beaded structure between the fibers, the diameter distribution was uniform, and the average diameter was 324 nm, exhibiting good spinnability. The contact angle of PCL fiber membrane to water was 137.08°, the highest oil absorption rates of engine oil, peanut oil and rapeseed oil were 36.73 g/g, 34.20 g/g and 30.63 g/g, respectively, and the oil retention rates were all above 55%. After five cycles of use, the oil absorption rates of the three oils could still surpass 15.0 g/g. It shows that the PCL fiber membrane has favourable hydrophobic performance, oil absorption performance, oil retention and certain recycling performance.
The nanofiber membrane prepared by electrospinning technology and the traditional method for oil pollution treatment have good hydrophobic property, oil absorption, recycling performance, environmental protection and other advantages, and has a good application prospects in the field of oil-water separation. At the same time, the research results can provide theoretical value and reference for replacing the shortcomings of traditional methods to deal with oil pollution.

Preparation and filtration properties of electrospun aramid nanofiber membranes

WANG Lingxiao, XU Guilong, TANG Min, LIANG Yun

2023, 31(1):  136-144.  DOI: 10.19398/j.att.202206047

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Meta aramid (PMIA) is a kind of high-performance fiber, which has many excellent properties such as high strength, high modulus, high temperature resistance, chemical corrosion resistance, dimensional stability and so on. It is widely used in the fields of high temperature protection, industrial filtration and new energy. With the research and development of nanofiber technology, PMIA nanofibers have received extensive attention in the filtration field due to their high specific surface area, micro effects, interface effects and many other characteristics. Electrospinning is one of the common methods to prepare nanofibers and it has the advantages of low cost, simple operation and continuous preparation of controllable nanofibers. At present, researchers have studied the basic conditions of PMIA dissolution and electrospinning process respectively, and prepared nanofiber filter membranes with high filtration efficiency by using special technologies such as electrostatic spray screen. However, there are problems such as relatively large average diameter of nanofibers, decreased filtration efficiency of nanofiber membranes, large pressure drop, high equipment requirements and complex process.
Firstly, we explored the influence of electrospinning process parameters, such as the concentration of solute in spinning solution, electrospinning voltage, feed flow rate and collection distance on the diameter and morphology of nanofibers, obtaining the optimal process parameters. Secondly, we explored the influence of the spinning time on the filtration performance of composite filter materials by controlling the spinning time so that nanofiber filter membranes with different thicknesses could be formed on the substrate. Thirdly, we compared the changing rule of the filtration performance of the electrostatic filter materials whose static electricity is eliminated by isopropanol vapor with that of the filter materials without eliminating static electricity. Finally, the thermal dimensional stability and thermogravimetric stability of electrospun filter materials were studied and analyzed. By controlling and optimizing the morphology of PMIA nanofibers, filter materials with high efficiency and low resistance could be obtained. The results show that when the spinning solution concentration is 8%, the spinning voltage is 20 kV, the feeding speed is 0.3 mL/h, and the receiving distance is 15 cm, the average diameter of the obtained nanofibers is small, the fibers are smooth and regular, and the morphology is good. When the spinning time is 5 h, the filtration efficiency of the nanospun membrane for NaCl aerogel particles with median particle size of 0.26 μm reaches 99.5%, and the resistance is only 123.8 Pa. After electrostatic treatment, the filtration efficiency can still reach 89.4%; the size of the nanofiber membrane is basically unchanged in the temperature range of below 290 ℃, and the thermal weight loss at 400 ℃ is only 5%.
The electrospun PMIA nanofiber filter material has good filtration performance, dimensional stability and high temperature resistance, and is easy to be prepared on a large scale. It has an important application prospect in the field of high temperature and high efficiency filtration.

Preparation and properties of PVC/PVDC blend membranes

ZHOU Yukai, QIAN Jianhua, YANG Jingjing, XU Kaiyang, MEI Min

2023, 31(1):  145-152.  DOI: 10.19398/j.att.202206032

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Polyvinyl chloride (PVC) is one of the main membrane materials in modern times. It has excellent acid and alkali resistance, microbial resistance, high mechanical strength, low price and other advantages, and is widely used in ultrafiltration, nanofiltration and other fields. However, the film forming performance of PVC is not very ideal, the water flux is low, and the toughness is insufficient, so it is easy to shrink and wrinkle spontaneously when gel is used. Therefore, the PVC film needs to be modified by blending to improve its performance. Polyvinylidene chloride (PVDC) has good film forming property, good mechanical properties, thermal stability and chemical resistance. Therefore, blending PVC and PVDC can make the film have both advantages. In addition, due to the poor hydrophilicity of PVC and PVDC, polyethylene glycol (PEG) can be used as an additive to modify the blend membrane, which can improve its hydrophilicity, pollution resistance and pure water flux.
In order to investigate the preparation and properties of polyvinyl chloride(PVC)/poly(vinylidene chloride) (PVDC) blend membranes, N, N-Dimethylacetamide (DMAC) was used as solvent to prepare PVC/PVDC blend membranes by phase inversion method. The compatibility of PVC/PVDC blend system, the surface morphology and cross-sectional morphology of blend membranes, as well as the effects of blend ratio and polyethylene glycol (PEG) mass fraction on pure water flux, rejection, dynamic contact angle and flux recovery were studied. At present, a lot of studies on the blending modification of PVC membranes have been done at home and abroad, but the study on the modification of PVC membranes with PVDC has not been reported yet. The results show that when the blending ratio is 4/6, the overall performance of the blend membrane is the best, the pure water flux is 212.9 L/(m²·h), and the rejection rate of bovine serum albumin (BSA) is 88.5% under the pressure of 0.1 MPa. The optimum mass fraction of PEG is 6%, and at this time, the pure water flux is 336.6 L/(m²·h), the interception rate is 81.6%, the instantaneous contact angle decreases from 81.1° to 74.5°, and the recovery flux rate increases from 52.7% to 85.7%. The results show that PEG can effectively improve the hydrophilicity and anti-protein pollution ability of the blend membrane.
In this paper, PVC/PVDC blend membranes are prepared by phase inversion method. The compatibility of PVC/PVDC blend systems is analyzed and discussed by measuring the shear viscosity of solutions with different blend ratios. At the same time, the surface and section microstructures of PVC/PVDC blend membranes are observed by field emission scanning electron microscopy (SEM), and the contact angle, pure water flux and flux recovery rate and the interception rate of bovine serum albumin (BSA) are tested to determine the optimal blend ratio. On this basis, the influence of PEG mass fraction on the performance of the blend membrane is studied to determine the optimal PEG content, which provides some directions for the material selection and modification of PVC blend membranes, and endows them with a broader market prospect in water treatment and sewage treatment.

Preparation of Co₂NiO₄ @ carbon cloth composite electrode and its application in glucose sensors

LI Saisai, ZHOU Jiamin WANG Menghu, ZHAO Jiazhe, WANG Lina, JIN Dalai

2023, 31(1):  153-162.  DOI: 10.19398/j.att.202206016

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The continuous improvement of people's living standards and living conditions is accompanied by health problems. One of the most significant problems is that the number of patients with diabetes is rising sharply, and at the same time, the people suffering from diabetes tend to be increasingly younger. Diabetes is a disease caused by insufficient insulin produced by the pancreas or inability to use insulin effectively, which is manifested by blood glucose concentration higher or lower than the normal range (4.4～6.6mM). As diabetes is a chronic disease, it will lead to many comprehensive complications, such as vision loss and renal failure. Research shows that strict carbohydrate control can improve the survival rate of diabetes patients and prevent complications related to type 1 and type 2 diabetes. Therefore, real-time monitoring of people's physiological blood glucose level is the key to the effective treatment of diabetes. Therefore, the development of electrochemical glucose sensors with high sensitivity, excellent selectivity and reusability has attracted extensive attention of many researchers.
Carbon cloth is a kind of commercial woven fabric. Due to its high conductivity, porous network, large surface area, good mechanical flexibility and strength, it is considered as an excellent substrate for building flexible electrode materials, and has potential development prospects in the fields of catalysis, energy storage and sensing. In recent years, various active substances such as noble metal simple substances, metal compounds and complexes have directly grown or been coated on the surface of carbon cloth. When used as glucose sensors, they exhibit excellent stability and electrochemical performance.
In order to obtain electrode materials for enzyme free glucose sensors with excellent sensing performance, the nano needle like precursor was in-situ grown on the surface of carbon cloth (CC) by hydrothermal method, and then Co₂NiO₄ nano needle like array was obtained by heat treatment to construct the Co₂NiO₄@CC composite electrode system. XRD, SEM and BET were used to characterize the phase, morphology and structure of the composite electrode material. On this basis, glucose was detected in the 0.1 M sodium hydroxide solution system using a self-built test platform. It shows good stability, wide linear range and excellent sensing performance. The test results show that the sensitivity of the Co2NiO4@CC electrode for glucose detection is 29.72 μA/(mM·cm²), detection linear range is 0.01 μM～11.5 mM, detection limit is 1.65 μM (S/N=3); the electrode material still retains 72.7% current response after 21 days of storage, and has excellent electrochemical sensing performance, good reusability and selectivity for glucose.
With the rapid development of nano materials and nano preparation technology, there are many innovative methods for the research of enzyme free glucose sensors. The adjustment of the structure, size, morphology and surface properties of nanomaterials will help to improve the sensitivity and selectivity of enzyme free glucose sensors. More importantly, the enzyme free electrochemical sensor based on nanocomposites breaks the limitations of enzyme sensors, and potentially becomes the next generation of sensing tools for low cost, high speed, and highly sensitive determination of glucose demand, promoting the development of glucose detection technology.

Textile Engineering

Production techniques and applications of segment color yarns

LOU Huan, LIU Qian

2023, 31(1):  163-175.  DOI: 10.19398/j.att.202204062

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Segment color yarns, with rich color changes, a strong sense of personalization, fashion, and color, three-dimensional and hierarchical effects and strong designability, play an important role in clothing, home textile design and other fields. In recent years, with the improvement of people's demand for personalized, fashionable, diversified and functional yarns and fabrics, the category of segment color yarns has been continuously expanded, and their production methods have become more diverse. There have also been extensive research and reports on yarn color design and control, yarn performance and quality.
At present, there are many production technologies of segment color yarns, which are mainly divided into dyeing method and mixing method. The dyeing method uses the traditional yarn dyeing process to dye different colors of dyes into the same yarn through segmented dyeing, which is more flexible and freer in the control of color distribution. The mixing method is to feed fibers of different colors at different speeds by modifying the mechanism and components at the drawing, roving or spinning points to achieve the effect of mixing fibers of different proportions at different sections of the same yarn sliver. The whole production process is more environmentally friendly.
The segment color yarn has various styles. With its irregular color segment, lively and natural style and strong artistic sense, it can develop textiles with rich and varied colors and patterns. By combining other fancy yarns, such as slub yarn and colored dot yarn, or other spinning technologies, such as Siro spinning technology and core-spun technology, new structured segment color yarns with multiple styles and characteristics can be developed, greatly enriching the product appearance. By selecting and matching different fiber materials such as cotton, wool, silk, hemp and chemical fiber, the excellent characteristics of fibers can be fully combined to develop high-quality segment color yarns to meet the needs of more fabrics. By grasping the principle of color mixing and the law of color change, the yarn can be color matched and the fabric pattern can be designed, so as to develop new and unique color yarns with different styles. Through the combination of functional yarns, the segment color process can be used in the blending of functional fibers to realize the development of functional segment color yarns and further expand the application field of segment color yarns. In order to improve the operational flexibility in the spinning process, digital control, such as three-channel digital ring spinning, can be used to spin segment color yarn. Through the coordinated control of servo drive and PCL, and with the combination of software and hardware, the flexible spinning production can be realized. In addition, in order to predict the forming effect of segment color fabrics, simulation technology can be introduced for simulating, which is convenient for the design and modification of patterns, thus improving production efficiency.
Nowadays, people's requirements for textiles are not limited to comfort and durability. Textiles with unique style and appearance effect are increasingly favored by consumers. Fancy yarns have become a hot topic in new product development. As a kind of fancy yarns with diversified colors and strong designability, the segment color yarn and the fabrics thereof can develop many new different styles through the integration of other spinning technologies, the combination of different raw materials, color matching, the combination of functional yarns and process optimization, which promote the development of textiles towards the diversification of raw materials, the enrichment of color patterns, product functionalization and production optimization, with great development space.

Experimental study on spinning core-spun yarn containing a metal wire based on the vortex spinning nozzle with air suction

WANG Xingbao, XI Chuanzhi, WANG Ke, WANG Jiayuan, PEI Zeguang

2023, 31(1):  176-184.  DOI: 10.19398/j.att.202206051

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Vortex spinning is a new spinning technology that adopts the swirling airflow formed inside the nozzle to form the yarn which is composed of a core made of parallel untwisted fibers and the spiral sheath fibers wrapping around the core fibers. This special two-layered structure makes vortex spinning especially suitable for spinning core-spun yarns. The core-spun yarn containing a metal wire fabricated by vortex spinning is a new type of conductive yarn. However, in the process of vortex spinning, the high-speed swirling airflow will make a portion of fibers overcome the twisting force to become lost fibers, which will reduce the amount of fiber on the yarn surface. This will result in the exposure of the metal wire on the yarn surface, which will deteriorate the yarn quality. Therefore, it is of great significance to design the vortex spinning nozzle with reduced lost fibers.
In order to reduce the amount of lost fibers during the spinning process of core-spun yarn containing a metal wire, the vortex spinning nozzle is designed and manufactured. According to the spinning principle, a vortex spinning nozzle with several air suction holes arranged on the wall of the yarn passage through the spindle is designed. The modified spindle is composed of the main body, air suction pipe and end cover. The main body and end cover of the spindle are manufactured by casting molding method with epoxy resin as the material. For the manufacture of air suction pipe, a micro twist drill is used to drill holes on the wall of the copper pipe with an outer diameter of 1.6 mm, an inner diameter of 1.3 mm, and a length of 73 mm. In order to study the effect of the suction airflow and different structural parameters of the suction holes on the fiber loss and yarn breaking tenacity, five air suction pipes with different parameters are designed and manufactured for the spinning experiments with the spindle without suction holes taken as the experimental control group. The method of measuring yarn linear density is used to indirectly characterize the amount of lost fibers under different working conditions. On this basis, the Minitab software is used to statistically analyze the measurement results with 95% confidence intervals. The Grubbs criterion is used to test whether there are abnormal values in the data. ANOVA is used to study the effect of suction hole diameter and axial length of air suction region on the fiber loss during the spinning process and yarn breaking tenacity. The results prove that compared with the traditional nozzle, adding air suction holes on the the wall of the yarn passage through the spindle can effectively reduce the fiber loss during the spinning process and increase the yarn breaking tenacity. The effect of hole diameter in the range between 0.2 mm and 0.4 mm on the amount of lost fibers is found to be insignificant, while the core-spun yarn exhibits highest tenacity at the hole diameter of 0.2 mm. As the axial length of air suction region changes from 25 mm to 34 mm, there is no significant effect on the fiber loss and breaking tenacity of yarn.
The results of this study can provide a new idea for the design of air-jet vortex spinning nozzle device.

Preparation and properties of ZrO₂/SiO₂ modified thermal insulation cellulose microfiber aerogel composite fabrics

FAN Hongxia, FENG Xinxing, JIN Wanhui, ZHANG Huapeng

2023, 31(1):  185-193.  DOI: 10.19398/j.att.202206042

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The new thermal insulation materials mainly achieve the thermal insulation effect by increasing the internal pores of the materials to accommodate more static air. Aerogel has the characteristics of high porosity, low thermal conductivity and low refractive index, and is widely used in the field of thermal insulation. Cellulose aerogels have the advantages of renewability, biocompatibility and biodegradability, and overcome the shortcomings of traditional inorganic gels, such as friability and difficulty in repeated use. However, the thermal stability of cellulose itself is poor, and cellulose aerogels cannot maintain stability in high temperature environment. Therefore, in order to improve its thermal stability, the cellulose is modified to make the aerogel prepared from the modified cellulose have good thermal insulation performance under high temperature environment. The strength of aerogel is generally low, so it is difficult to use it as an insulation material alone. In order to improve the low strength of the aerogel and give the fabric good thermal insulation performance, the modified cellulose aerogel is compounded with ordinary fabrics to obtain a cellulose aerogel composite fabric with good mechanical strength and thermal insulation performance.
The precursor solution was prepared with a certain proportion of zirconium oxychloride /tetraethyl silicate as the precursor and yttrium nitrate as the stabilizer. The cellulose microfibers (CMF) after pre-oxidation treatment are uniformly dispersed in the precursor solution to form a mixed solution. The CMF aerogel composite fabric modified by ZrO₂ and SiO₂ was prepared by casting the mixed solution on the fabric, adopting the sol gel method and freeze drying treatment. Fourier infrared spectroscopy (FTIR) was used to analyze the degree of crosslinking of CMF, and thermal imaging was used to measure the thermal insulation effect of the aerogel composite fabric. The mechanical properties and wearability of the aerogel composite fabric were explored by measuring the breaking elongation, permeability and thickness of the fabric. The results show that the aerogel layer of the aerogel composite fabric is well bonded to the surface of the fabric; the CMF aerogel is successfully doped with Zr and Si; the aerogel composite fabric has good heat insulation performance on 37 ℃ and 100 ℃ hot plates; the air gel composite fabric can still maintain good heat insulation performance after washing and friction test.
In this paper, the modified CMF aerogel composite fabric is prepared by compounding the ordinary fabric with a new modified CMF aerogel thermal insulation material. The preparation process is simple and environmentally friendly. The aerogel composite fabric has excellent heat insulation performance and good wearability. The research results can lay a foundation for the application of cellulose aerogels in the field of heat insulation and warmth preservation.

Effects of different laser engraving levels on the appearance and characteristics of flannelette

LÜ Xueshan, LI Ziyu, WANG Xueqin

2023, 31(1):  194-203.  DOI: 10.19398/j.att.202205002

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In recent years, because of its unique advantages, laser engraving process is not only widely used in electronics, packaging, advertising, and other industries, but also more and more widely used in textiles, especially in the soft decoration industry in the home space. Combining the laser engraving process with the form of fabric wall, the fabric can present a multi-layer three-dimensional effect through laser engraving, breaking the previous two-dimensional flat pattern method and making the indoor space picture variable. The gloss and softness of the flannelette fabric can create a modern light luxury style. Therefore, this paper uses laser engraving technology to innovatively carry out appearance feature engraving experiments on flannel cloth to explore the effect form achieved by laser engraving on flannel.
By analyzing the influence of laser engraving on the appearance and characteristics of flannel at different levels, the three-dimensional effect of laser engraving on flannel was further explored. Experiments were carried out on 11 engraving levels on flannel, and the effect analysis was carried out from the color, thickness, and surface morphology of the fabric. The laser engravement process was applied to the flannel, and the three-dimensional layered effect of laser engraving on the flannel was realized through multi-level experimental exploration. Then the influence of laser engraving process on the appearance effect of flannel was analyzed. The results show that the layers of laser engraving have a great influence on the color brightness value of flannel, and four distinct categories are obtained through chromatic difference and cluster analysis, and no significant differences between B0-B50, B60 and B70, B90 and B100 engraving levels are found. The thickness of the fabric decreases as the engraving level increases, reaching its thinnest at B0 and its thickest at B90. At the same time, the change in the thickness of the fabric is also accompanied by the change in the brightness of the fabric. As the layers of laser engraving deepen, the fibers are gradually melted into flat surfaces, accompanied by tiny holes. The results of this study provide a basis for the application of laser engraving technology in flannel.
This paper chooses to study the impact of laser engraving process on the appearance effect of flannel, through laser engraving level analysis and thickness analysis, can make layered decorative paintings or wall cloth and other household practical products, which also provides new development ideas for the soft decoration industry. The research results can provide practical reference value for the subsequent application practice of laser engraving on different fabrics, and can be applied to more diverse scenarios.

Dyeing and Finishing & Chemical Engineering

Preparation of zinc phthalocyanine grafted cellulose nanofiber and its dye degradation properties

WANG Zhankai, XU Shilong, YANG Shiyu, HU Yi, HU Liu

2023, 31(1):  204-212.  DOI: 10.19398/j.att.202207011

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In recent years, wastewater discharge accounts for a large proportion of environmental pollution, posing a great threat to the environment and human health. Printing and dyeing wastewater has been paid much attention in the field of wastewater treatment and reuse for its high chroma, complex components and large amounts of discharge. The available dye-degradation methods including physical adsorption and biological treatment have problems like secondary pollution, high cost and energy-consuming, while the photocatalytic dye-degradation method based on the inorganic semiconductor, though famous for its high efficiency, also has defects such as difficult material recovery and requiring UV light illumination. Therefore, it is necessary to develop new recyclable photocatalytic materials for efficient dye decomposition in wastewater treatment.
In order to construct highly-efficient, recyclable and visible light responsive dye degradation materials, we started from the excellent photocatalytic performance of organic photosensitizers and the high specific surface area of nanofiber membrane, synthesizing and characterizing tetracarboxyl modified symmetric zinc phthalocyanine organic photosensitizer, and then covalently grafted it onto the cellulose nanofiber obtained by electrospinning technology via N,N'-carbonyldiimidazole catalytic esterification method. The zinc phthalocyanine photosensitive group has strong visible light absorption and high singlet oxygen quantum yield. However, due to the high planarity of the structure, the intermolecular aggregation can lead to the reduction of photosensitive activity. In this paper, zinc phthalocyanine photosensitizer was covalently loaded on the surface of nanofiber membrane to provide space for molecular extension, which could reduce the aggregation of zinc phthalocyanine derivatives and improve the photosensitivity. The chemical structure and appearance of the novel zinc phthalocyanine functionalized nanofiber membrane were analyzed, its photocatalytic mechanism was further studied through reactive oxygen capture technology, and its dye degradation performance and recycling ability under visible light condition were explored. It is found that the zinc phthalocyanine photosensitizer functionalized nanofiber membrane has excellent singlet oxygen generation ability under near-infrared light irradiation, and the adsorption ability of the nanofiber membrane to dyes can help alleviate the problem of weak degradation ability caused by short singlet oxygen lifetime. The zinc phthalocyanine functionalized nanofiber membrane has the degradation performance to methylene blue under visible light irradiation, and it can be recycled for reuse.
The photosensitive activity of zinc phthalocyanine photosensitizer provides new enlightenment for photocatalytic degradation of dyes. The covalent grafting of zinc phthalocyanine photosensitizer onto the cellulose nanofiber membrane can achieve efficient degradation of dyes under visible light catalysis, and it is easy to recover, which provides a new idea for the development of new efficient and recyclable wastewater treatment materials.

Analysis of the effect of fine-washing conditions on the properties of down materials

WEI Yuhui, ZHOU Shijie, XU Zhongtong, DING Xuemei, WU Kaiming

2023, 31(1):  213-220.  DOI: 10.19398/j.att.202206014

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Down materials, as a kind of animal-derived materials, are obtained mainly by means of mechanical or manual depilation after blanching and slaughtering, and adsorbs soil, dust, oil, dander, bloodstain, feces, small blood vessels, bacteria and viruses and feathers and other impurities. If the surface stains of down materials are not washed in time, they will not only reduce the quality of down materials (discoloration, unpleasant odor, hardened feel, low fluffiness, poor warmth, etc.) to affect the later use, but also breed harmful bacteria and viruses causing respiratory tract, intestinal diseases and skin allergies, itching and other uncomfortable symptoms of the body, and even endangering safety of life. However, the current studies on down material mainly focus on surface modification, antibacterial finishing, down material performance optimization and evaluation, product design, etc., and there were few studies on the washing mechanism and green-washing technology of down materials. Additionally, fine-washing for down materials is an important link to remove the down material adhesion on the surface of water-soluble, oily, solid, insoluble organic matter and other stains, to achieve the deashing, degreasing, deodorization, disinfection and sterilization purposes, but also an important operation to obtain good flexibility, resilience, and warmth. In addition, 70% of the down material enterprises in China are facing the problems of "high pollution, high energy consumption and performance degradation after washing", which is contrary to the green and sustainable production strategy advocated by our country.
In order to develop an efficient and green washing process for down materials, we took the down materials after initial washing as the experimental object, systematically investigating the relationship among different water temperatures, bath ratios, main washing times, washing speeds, rinsing times, detergent dosages of fine-washing stage and the properties of down materials after washing. It is found that the water temperature, detergent dosage, main washing speed and washing time are the main factors affecting the cleanliness of down materials after washing, while the main bath ratio, rinse bath ratio, rinse speed and rinse times have relatively little influence on the cleanliness of down materials after washing. The influence of fine-washing process conditions on the fluffy degree of down materials is not obvious, but the fluffy degree of down materials is reduced because of excessively long washing time and excessively high washing rotation speed. The influence trend of fine washing technology on the residual value and oxygen consumption of down material after washing is the same, that is, the water temperature, detergent dosage, main washing time and main washing speed are the main factors affecting the residual value and oxygen consumption of down materials while the rinsing frequency, main bath ratio, rinsing bath ratio and main bath speed have insignificant influence; the amount of detergent, rinse times, bath ratio (main bath ratio and rinse bath ratio) and water temperature are the main factors affecting the odor of downs while the washing speed, main washing time and rinse speed have insignificant influence. The results provide theoretical guidance and technical support for down manufacturers to develop efficient and environmental-friendly washing condition of being suitable for down materials.

Steam degumming process and properties of silk fabrics

YE Yanli, GUO Jiaxing, FU Yaqin, CHEN Wenxing, JIANG Wenbin

2023, 31(1):  221-231.  DOI: 10.19398/j.att.202206038

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The culture derived from mulberry silk and its products has a long history. Silk fabrics are sought after by the public because of their characteristics of softness and fineness, soft brightness, flowing and draping, and skin-friendly property. Silk as a fabric raw material is composed of silk fibroin and sericin. Silk sericin is secreted by the silk gland of the silkworm and wrapped in the periphery of the silk fibroin, accounting for 20% ~ 30% of silk and playing a protective and sticky role. However, the presence of sericin can cause fabrics to feel stiff with poor softness, so most silk textiles on the market are refined to remove sericin. The principle of degumming is based on the difference between the characteristics that sericin is soluble in acid, alkali and hot solution, and that silk fibroin only swells but is not soluble in water, and the mulberry silk and its fabric are soaked in thermal degumming solution to realize the separation of sericin and silk fibroin. The common degumming methods will pollute the environment with the degumming waste liquid, and the sericin in the waste liquid is not easy to recycle, leading to the waste of resources. On the other hand, the storage conditions of biological enzymes are strict, which leads to the increase of degumming cost. Other degumming methods also have problems such as low debonding efficiency and high equipment requirements. Therefore, it is urgent to explore a degumming method that is efficient to clean and can be effectively controlled in mulberry silk fabrics.
As heating changes water from liquid to saturated water vapor with extremely high energy and strong penetration ability, and the temperature of saturated water vapor is controllable, it also presents the advantages of efficient and uniform degumming in the field of hemp fiber degumming. Therefore, in view of the above problems, we proposed a new process of clean and efficient steam degumming without any additives and explored the controllability of degumming silkworm silk fabrics treated by water vapor, which can reduce the waste of water resources, avoid the pollution of chemical waste liquid and control the degumming effect. In this paper, the mulberry silk crepe de chine fabric was taken as the degumming object, and the degumming rate of the mulberry silk fabric under different conditions was analyzed by controlling different steam temperatures and steam degumming times by using a single factor experimental method. The steam degumming process that can be completely degummed was selected, and the sodium carbonate degumming method was used as the control group to analyze and compare the micromorphology, secondary structure, tensile properties and drape properties of the mulberry silk fabrics after degumming. The results show that at the steam temperatures of 105 ℃ and 110 ℃, the fabric degumming rate is linearly positively correlated with the debonding time. Under the conditions of 115, 120 and 125 ℃, the fabric degumming rate and degumming time are logarithmically functioned. When the steam temperature is 125 ℃ and the degumming time is 45 min, the mechanical properties of the silk fabric are the best, and the drape performance is slightly poor. The microstructure and secondary structure are not significantly affected, and the degumming efficiency increases by 45.83%.
The new steam degumming process is feasible and controllable for the degumming of mulberry silk crepe de chine fabric and improves the degumming efficiency. This new degumming process makes it possible to replace conventional chemical degumming, and also provides a theoretical basis for the innovation of debonding methods in the industry.

Small bath ratio dyeing process and properties of the natural dyes of litchi seeds for cotton knitted fabrics

XU Liang, SHEN Linqi, YU Zhicheng, WANG Lei, XIE Guangyuan

2023, 31(1):  232-239.  DOI: 10.19398/j.att.202207058

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With the improvement of people's quality of life and the enhancement of environmental awareness, more and more attention has been paid to natural dyes. Natural dyes originate from nature, belong to nature, have good biodegradability, reasonable use of natural dyes, and can realize the real green and sustainable development of natural dyes. Studies have shown that natural dyes can not only dye a unique soft color, but also give added value to the fabric, such as endowing the dyed fabric with a unique aroma, anti-mosquito, anti-bacterial, anti-UV functions and such. However, the development of natural dyes is affected by their limitations such as the poor reproducibility of natural dyes dyed fabrics, low extraction rate, poor color fastness and incomplete chromatography, which seriously restricts the industrialization of natural dyes. Therefore, faced with the increasing demand for dyes, the development and research of natural dyes is urgent. In this paper, we extracted natural dyes from waste lychee seeds, discussed the cationic modifiers and their modification mechanism on cotton fabrics, optimized the modification process of cotton fabrics and natural dyes' dyeing process to test the color fastness and explored the effect of mordant and antioxidant on enhancing the color fastness to sun.
In order to effectively utilize the waste resources of litchi seeds, the effective components of litchi seeds were extracted and applied to dye cotton knitted fabrics. Firstly, the cationic modifier D of quaternary ammonium salt was used to modify the pure cotton knitted fabric, and the modification process was optimized. The Zeta potential and infrared spectrum of the pure cotton knitted fabric were measured before and after the modification. Then the dyeing process of the natural dyes of lychee seeds for cotton knitted fabrics was optimized. Finally, the color fastness of the natural dyes of lychee seeds was improved by post-dyeing and antioxidant treatment. In this experiment, lychee seeds were selected as the extract to achieve the reuse of waste resources. The extraction method of enzyme and soda ash was adopted to improve the extraction rate of dye. In this paper, small bath ratio is used to reduce water consumption and energy consumption, and reduce the use of chemical additives. The results showed that the pure cotton knitted fabrics dyed with lychee seeds had a high dyeing K/S value, and the color fastness to soap washing and friction was above grade 3, and the color fastness to sunlight was up to grade 4. The optimal modification process requires a modifier of D30 g/L and sodium hydroxide of 10 g/L at 80 ℃ for 30 min. The dyeing process requires a dyeing pH value of 7 and a dosage of sodium sulfate of 0 g/L at 90 ℃ for 60 min.
Cotton is one of the most important raw materials in the field of textile and has a long history of application. As early as thousands of years ago, human beings began to cultivate cotton. Because of its excellent moisture absorption, softness and air permeability, cotton has never been eliminated from the field of textile. Natural dyes are applied to cotton fabric dyeing. Nowadays, under the guidance of the concept of advocating nature, green, simplicity and comfort, cotton has been increasingly valued and loved by people. The ecological and environmental protection of cotton fabrics combined with natural dyes comes from the natural green health, which can bring the all-natural cotton fabrics, and is in line with modern people's pursuit of ecological green. Therefore, the research and development of natural vegetable dyes and cotton textile dyeing have broad market prospects.

Identification and inhibition of microbes on mildewed cotton clothes

XIAO Yuyan, REN Zehua, YANG Yu, GAO Yuan, LIU Jianli

2023, 31(1):  240-247.  DOI: 10.19398/j.att.202205047

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During the storage or wearing process of cotton clothing, "mildew" phenomenon is caused by microbial contamination, which forms mildew spots on the clothing, produces odor, and affects the appearance and service life of clothing. Wearing moldy clothes is likely to cause cross-infection of the skin and there are health risks. Fungi can decompose fibers to be nutrients, and metabolites secreted by the human body such as sebum and sweat adsorbed on clothing can also provide nutrients for microorganisms to reproduce and grow on them. Molds also secrete organic acids during the growth process to erode the fabric. Cotton clothes in the daily life of the environment is easy to be contaminated by microorganisms, and is more prone to molding in the humid rainy environment. However, there are differences in the types of mold on different fabrics. Therefore, it is necessary to identify the types of mold microorganisms on clothing in different regions, and use effective bacteriostatic agents to protect textiles and prolong their service life.
In order to determine the type of mildew on cotton clothes, so as to inhibit the mildew of cotton clothes, the mold on the moldy clothing was extracted, and was cultured and purified in PDA medium under the appropriate temperature and humidity. Single mold and dominant mixed strains were inoculated on cotton fabrics. In order to simulate the real growth of mold on cotton clothes, human sebum was used as microbial nutrient. Potassium sorbate, zinc sulfate and sodium benzoate were used as antibacterial agents to observe the growth of fungi on cotton fabrics. The number of molds on it was counted by a mold counter to explore the antibacterial effect of the three inhibitors and the optimal addition amount. Finally, seven kinds of molds were obtained. The results showed that the dominant fungi causing mildew of cotton fabrics were Aspergillus and Penicillium. The seven fungi were identified as Rhizopus stolonifera, Penicillium apicale, Aspergillus flavus, Cladosporium budding, Penicillium citrinum, Aspergillus versicolor and Phoma sp. by ITS sequence analysis and homology comparison. It was found that the best bacteriostatic concentrations of different molds were different, and the bacteriostatic effect of zinc sulfate was the best. When the addition of potassium sorbate and zinc sulfate was 0.12g/100mL and the addition of sodium benzoate was 0.14g/100mL, the optimum inhibitory concentration of the mixed dominant fungi on cotton fabrics was obtained.
Identification of mildew fungi on cotton clothes provides experimental reference for elucidating the mechanism of cotton clothes mildew. The optimum concentration of antibacterial agents for cotton fabrics explored lays an experimental foundation for the antibacterial technology of cotton fabrics in the storage end.

Comprehensive Review

Research progress of nanofibers for treatment of biofilm-related infections

ZHAO Shuying, ZHANG Yingjie, LI Yan, WANG Lu

2023, 31(1):  248-258.  DOI: 10.19398/j.att.202207023

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Bacterial biofilms refer to a three-dimensional structure group containing multiple cells formed by bacteria embedded in extracellular polymers secreted by themselves. Compared with planktonic bacteria, bacterial biofilms have more complex morphological structures and stubborn physiological characteristics that are difficult to remove. Implantable medical device infections and chronic infections caused by bacterial biofilms have a serious impact on patients' physical and mental health and medical burden, which has become a major challenge in the current medical and health field.
In recent years, nanofibers have become the dominant carrier of anti-biofilm agents to cope with bacterial biofilm-induced infections due to their high specific surface area and strong surface design. By blending antibacterial agents with polymers during electrospinning or functionalizing nanofibers after electrospinning, nanofibers with anti-biofilm properties can be obtained. According to the characteristics of bacterial biofilms, a series of nanofibers have been developed to remove bacterial biofilms from the principles of preventing biofilm formation, targeting extracellular polymeric matrix, inhibiting signal molecules, and even achieving the synergy of multiple treatment methods, which has become a promising biofilm treatment strategy.
Specifically, in order to prevent the formation of biofilms, researchers inhibit bacterial adhesion by regulating the diameter of nanofibers and changing the hydrophilicity of fibers or design a surface that enhances fibroblast adhesion to prevent the formation of bacterial extracellular polymers, so that planktonic bacteria cannot form biofilms. In the study of targeted destruction of extracellular polymer matrix, researchers combine nanofibers with microneedle arrays to form composite patches, and transport the drugs loaded on the fibers to the interior of the biofilm by the penetration of microneedles, or combine enzymes and photodynamic therapy that degrade extracellular polymer components onto nanofibers to play a role in targeted destruction. In addition, in the inhibition of signal molecules, the anti-biofilm agents that can inhibit the signal molecules including the quorum sensing quenching enzyme, furan derivatives, and nitric oxide are mainly loaded onto nanofibers, so as to achieve the effective removal of bacterial biofilms.
In summary, nanofibers as a carrier of integrated antibacterial agents or a platform technology that integrates multiple therapeutic methods have emerged in the field of biofilm therapy. Nevertheless, the treatment of bacterial biofilm infection based on nanofibers is still in the ascendant. First, a mixed model of biofilm infection should be established in subsequent studies to evaluate the therapeutic effect. Secondly, in order to avoid drug resistance caused by the use of conventional high-dose antibiotics, antibiotic replacement therapy based on nanofibers should be expanded as far as possible to establish synergistic integrated therapy. At the same time, nanofibers as antibacterial agent delivery carrier also have the problem of explosive release and low release of antibacterial agent. Finally, multi-functional dressings can be established for chronic wounds to broaden application scenarios.

Research progress on the thermal insulation performance of 3D spacer fabrics

RUI Ke, HE Jiazhen

2023, 31(1):  259-268.  DOI: 10.19398/j.att.202206022

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3D spacer fabrics, also known as sandwich fabrics, are 3D structure fabrics composed of a number of spacer yarns connecting the upper and lower two surface fabric layers. The special 3D structure allows a large amount of static air to be stored in the spacer layer, and the static air is the medium with the smallest thermal conductivity in nature, which makes 3D spacer fabrics have better heat insulation performance than ordinary single-layer fabrics and have great development space as a high-performance thermal insulation material.
3D spacer fabrics, boasting excellent thermal insulation performance, light weight, excellent moisture absorption and breathability, anti-compression, high strength, etc., have broad application prospects in the fields of medical supplies, personal protective equipment, smart textiles and energy resource conservation. In the field of medical supplies, wound dressings made of spacer fabrics can reduce the heat loss of wounds and facilitate wound recovery. In the field of personal protective equipment, spacer fabrics can enhance the thermal protective performance of thermal protective clothing and reduce the heat loads of the wearer. In the field of smart textiles, spacer fabrics can be used to develop flexible thermoelectric systems to regulate human body temperature. In the field of energy resources, thermal insulation panels made of spacer fabrics, solar steam power photothermal materials, and transparent heat insulation materials can reduce energy loss and improve the utilization rate of energy resources.
To further expand the application field of 3D spacer fabrics so that the spacer fabrics can meet the demand for material thermal insulation performance in many fields, spacer fabric composite thermal insulation materials are an important means to enhance the thermal insulation performance of spacer fabrics. Spacer fabrics compounded with low thermal conductivity barrier insulation materials can enhance the insulation performance by reducing thermal conduction and thermal convection. The spacer fabrics composite reflective insulation materials can reduce the radiation absorbed by the fabrics and enhance the radiation reflectivity of the surface of the spacer fabrics, thus enhancing the thermal insulation performance of the spacer fabrics. The spacer fabrics with radiant heat insulation materials can enhance the heat insulation performance of the fabric by emitting the absorbed radiant heat into the environment.
The 3D spacer fabrics contain a large amount of static air, and have excellent thermal insulation performance, as well moisture absorption and permeability, energy-absorbing cushioning, etc., which can meet the needs of functional fabrics in different fields. At present, research on the thermal insulation performance of spacer fabrics is mainly carried out for knitted spacer fabrics. Although woven spacer fabrics are often used as the reinforcement of 3D composite thermal insulation materials, their own thermal insulation performance has not been fully studied, so the investigation of the factors influencing the thermal insulation performance of woven spacer fabrics is the key to expanding their application scope. Meanwhile, the establishment of a heat transfer model based on the microscopic characteristics of spacer fabrics can help researchers optimize the structure of spacer fabrics to enhance the thermal insulation performance. Finally, the development of high-performance spacer fabrics' insulation materials based on fiber raw materials, insulation materials and compounding methods is an important means to broaden their application fields.

Application progress on preparation of covalent organic framework membrane materials and their application in water treatment

MA Teng, LIU Guojin, JIN Wanhui, ZHU Hailin, LEI Caihong

2023, 31(1):  269-284.  DOI: 10.19398/j.att.202208002

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In recent years, with the rapid development of global industrialization, the pollutants contained in industrial wastewater are toxic and difficult to degrade, which seriously affects human health. Covalent organic frameworks (COFs), a new type of porous framework material connected by strong covalent bonds, have attracted wide attention in the fields of photocatalysis, sensing, adsorption and separation, drug delivery and energy storage due to their low density, high porosity, good stability and modifiable framework structure. With the deepening of research, it is found that the use of COFs materials with dense pore structure and surface charge properties can remove pollutants such as textile dyes, toxic heavy metals and salt ions in wastewater, and the effect is better than that of some commonly used filter materials on the market, showing a broad application prospect in the field of sewage treatment.
Currently, there are many kinds of COFs materials, and the differences in internal groups and chemical bonds make their properties different. In the field of water treatment, imine or triazine COFs materials prepared by solvothermal synthesis or ionothermal synthesis are usually selected. Although the crystallinity of such COFs materials is low, the internal stable chemical bonds can keep them stable in water. According to the principle of topological structure design, COFs materials with different pore structures were prepared. Using the regular frame structure of COFs, the performance of COFs materials was improved by functional modification, which greatly expanded its application field. Traditional COFs materials which are mostly powder are difficult to recycle and easy to cause secondary pollution. Changing the use form of COFs materials is the main method to solve this problem. At present, aerogels and separation membranes based on COFs materials have been prepared. Membrane materials are widely used in the field of water treatment because of their recyclability, low energy consumption and high compatibility. The membrane material prepared based on COFs improves the performance and solves the problem that COFs powder is not easy to recycle.
At present, composite membranes and mixed matrix membranes based on COFs have been prepared, showing excellent results in the field of water treatment. Based on the pore size of the membrane, the interception of pollutants is a common method in sewage treatment. The dense pore structure of COFs membrane can intercept dye molecules, heavy metal ions and salt ions in water. Adsorption is another common method in wastewater treatment. The high specific surface area of COFs membrane makes it have excellent adsorption capacity. At the same time, the functional modification of the frame structure can change the surface charge of the membrane and improve its adsorption capacity for pollutants with different ionic properties. And the introduction of hydrophobic or hydrophilic groups inside the framework can also make the COFs membrane have the ability of oil-water separation.
The effect of COFs materials in the field of water treatment shows that they have great application potential in this field. Expanding the form of COFs, and improving performance and expanding application fields through functional modification are the research hotspots of COFs materials. However, there are few types of COFs materials suitable for water treatment, and the current preparation yield of COFs materials is low. Therefore, it is necessary to increase the research on the synthesis of COFs materials, explore and find COFs materials suitable for water treatment, and promote the development of water treatment.

Research progress of formaldehyde-free wrinkle resistant finishing agents for cotton fabrics

LIANG Yajing, YAO Jinbo, FENG Mao, NIU Jiarong

2023, 31(1):  285-292.  DOI: 10.19398/j.att.202207061

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Cotton fabrics are popular for comfortable handle, good breathability, anti-static electricity and affordable prices, but they have the disadvantages of poor elasticity, proness to wrinkle, and can not maintain a smooth appearance in the process of wearing. In order to improve the poor anti-wrinkle properties of cotton fabrics, and conform to the philosophy of environmental protection, the research of formaldehyde-free anti-wrinkle finishing agents has been increasingly extensive and has become the basic requirement of the new technology of anti-wrinkle finishing. Based on the principle of anti-wrinkling, we summarize three kinds of formaldehyde-free anti-wrinkling finishing agents, namely polymer, molecular crosslinked and molecular crosslinked polymers.
Polymeric anti-wrinkle finishing agents realizing anti-wrinkle by resin deposition are mainly chitosan polymers. There are many amino groups and hydroxyl groups in the structure of chitosan, which can be diffused and deposited well to the amorphous region of the fiber. The finished fabric has high strength retention rate, high dye uptake and excellent antibacterial properties, but it has some shortcomings such as poor wrinkle resistance, yellowing and poor hand feel. It needs to be mixed with other finishing agents or modified.
Molecular cross-linked anti-wrinkle finishing agents realize anti-wrinkle by covalent cross-linking and mainly contain polycarboxylic acids, aldehydes and ionic crosslinking compounds. Esterification crosslinking occurs between polycarboxylic acid finishing agents and cellulose macromolecules in cotton fabrics, the finished fabric has excellent wrinkle resistance, good whiteness and washability, but the strength decreases obviously and the cost is high. The above-mentioned finishing agents are often used in combination with other anti-wrinkle finishing agents or mixed with new polycarboxylic acid anti-wrinkle finishing agents in order to obtain an excellent anti-wrinkle effect at a low cost. The aldehyde finishing agents have an aldolization with the hydroxyl groups on the cotton fabric. The finished fabric has high fastness to chlorine damage and low cost, but it has obvious strength loss, yellowing and a pungent smell. The ion-crosslinked finishing agents need the cotton fabric to be ionic modification before ion-crosslinking. The finished fabric has less strength loss and good whiteness, but poor crease resistance.
The molecular cross-linked polymer finishing agents achieve an anti-wrinkle effect through the synergistic effect of resin deposition and covalent cross-linking, with the resins mainly including reactive silicone and waterborne polyurethane. The reactive silicone is often used as a modifier to improve the anti-wrinkle properties of other finishing agents, with good handle and high strength retention rate. The waterborne polyurethane can improve the wrinkle resistance of the finished fabric by improving its molecular structure, and enhance the strength and wear resistance of the finished fabric.
In the future research of anti-wrinkle finishing agents, it is necessary to increase the research of green environmental protection finishing agents such as chitosan and waterborne polyurethane, so as to reduce the cost and broaden the function.

Research status and development trend of vitamin E loaded cosmeto-textiles

LI Shiya, JIN Xiaoke, TIAN Wei, LI Yanqing, ZHU Chengyan, ZHANG Hongxia

2023, 31(1):  293-300.  DOI: 10.19398/j.att.202206002

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With the progress of the times, people's awareness of their skin health care has been growing in recent years, and functional textiles for skin health have increasingly attracted people's attention and pursuit. Vitamin E loaded cosmeto-textiles are textiles that add vitamin E to textile materials to play a skin care function. Compared with traditional skin care products, vitamin E loaded cosmeto-textiles have a longer time and a larger area of close contact with skin, and their ingredients cover the skin more evenly. Moreover, because of the barrier effect of the fabric, the skin care effect is much better.
Due to the unstable properties of vitamin E, it can not be directly added to textiles, and must be transformed into vitamin E derivatives or loaded by carriers to maintain its biological activity. At present, vitamin E loaded cosmeto-textiles are mainly prepared by blending spinning or finishing. Specifically, vitamin E is first converted into its derivatives or loaded by various carriers such as cyclodextrin, microcapsule, microemulsion and sol-gel to maintain its biological activity, and then skin care functional fibers containing vitamin E are produced by spinning or the vitamin E is fixed on the fabric by after finish. The conversion technology of vitamin E derivatives is to transform vitamin E into stable derivatives through structural modification to ensure that it can play a stable role in the body, and this process is suitable for the preparation of disposable products. Cyclodextrin is an organic substance, which can wrap up vitamin E and protect it from oxidation and degradation. Vitamin E microcapsule is a kind of micro particle formed by coating vitamin E with polymer film materials. It can protect the stable existence of vitamin E and has excellent slow release performance. Microcapsule is one of the most widely used preparation technologies in vitamin E loaded cosmetotextile products in recent years. Microemulsion can be used as the carrier of vitamin E to make it better dispersed in liquid and improve its solubility and volatility in spinning solutions or finishing agents. Nonetheless, due to a variety of unavoidable shortcomings, the use of microemulsion has gradually decreased currently. Sol-gel method can solidify and embed vitamin E and the gel can form a close interaction with fabric fibers. However, this method requires a large number of organic compounds, with high cost and long processing time, so it is rarely used at present.
The skin care properties of vitamin E loaded cosmeto-textiles are characterized by vitamin E content, vitamin E slow release property and washing resistance.
At present, the crux of difficulties for the study of vitamin E loaded cosmeto-textiles mainly falls into two points: how to better control the release of vitamin E in textiles and how to improve the washing resistance. In order to better solve the above problems, we can start from the following aspects: first, it is necessary to optimize the preparation process, start from a more refined production level, and make the raw material preparation closer to the nanometer level; second, it is necessary to introduce new technologies such as solid lipid nanoparticles embedding technology and the dermotextile technology to find a better production mode; third, the formulation and improvement of relative testing methods and standards are also of great significance for the development of vitamin E loaded cosmeto-textiles.