Abstract: 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.

Key words: graphenes, carbon nanotubes, knitting, electro-thermal performance, electrical conductivity

摘要： 为了研究石墨烯/碳纳米管(GNs/CNTs)功能针织面料的结构与性能,选用3种不同组织涤纶针织面料,采用简单的控压喷涂法制备GNs/CNTs功能面料,通过SEM和FTIR分析GNs/CNTs喷涂分布情况,并对复合织物进行断裂拉伸测试、导电性能及电热性能测试,结果表明:GNs/CNTs呈相互缠绕勾连状态均匀粘附在涤纶针织面料纤维和纱线表面且未在织物表面成膜,织物结构清晰可见;GNs/CNTs能改善织物的力学性能和导电性能,GNs/CNTs网眼织物的电导率高达1 567 S/cm;GNs/CNTs功能针织面料在低电压下具有较好的电热性能,在不同组织面料中表现各异,其中纬平针织物升温速率快且发热效率高,网眼织物在10 V电压下可在15 s内升温至116.3 ℃。GNs/CNTs功能针织面料在智能服装、医疗保健等方面有良好的应用前景。

关键词: 石墨烯, 碳纳米管, 针织, 电热性能, 导电性