关键词: 桑蚕丝织物, 蒸汽脱胶, 脱胶率, 微观结构, 拉伸性能

Abstract: 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.

Key words: mulberry silk fabric, steam degumming, degumming rate, microstructure, tensile property