Study On Properties Of Vinylon-milk Fiber And Knitted Fabrics With Size Stability

Milk fiber is a new kind of regenerated protein fiber. Nowadays vinylon-milk fiber has attracted much attention in textile market because of its light specific gravity, soft handle, subdued luster, good wet permeability, and it is comfortable and beneficial to people's skin, but it has demerits of poor form retention and heat sensitivity. During the wet processing, vinylon-milk fiber has shown the following severe problems: low whiteness index of bleached fiber, poor dyeability for dark color, dull color of pale dyed fiber, poor level dyeing property, poor resistance to wet heat, rigid hand after wet processing at high temperature, loss of milk protein after improper wet processing.This thesis paid some emphasis on the resistance to wet and dry heat of vinylon-milk fiber and the dimensional stability of the knitted fabric. This work aimed at solving the problem arising in the development and practical production of vinylon-milk fiber. In this paper, the structure and properties of vinylon-milk fiber were first analyzed, and then their resistances to wet and dry heat, dimensional stability of knitted fabric were studied in detail.The results showed that vinylon-milk fiber had the general resistance to dry heat. When treated below 180℃, vinylon-milk fiber exhibited very low shrinkage, small change in whiteness and strength, but reduced dyeability. The results indicate that the safe and highest temperature of xerothermic treatment is 180℃, The properties of vinylon-milk fiber had no changes when treated below this temperature. When treated above 180℃, vinylon-milk fiber was easily subjected to thermal degradation and formed a yellow degradation substance.Vinylon-milk fiber had the poor resistance to wet heat. When treated above 90℃, vinylon--milk fiber exhibited the severe shrinkage and yellowing, hard handle, the great decrease in breaking strength and adhesive aggregation. Thus the temperature should be controlled bellow 90℃, when vinylon-milk fiber was treated in hot water. The results indicate that milk protein was hardly lost during treatment in water at high temperature, but the regularity of PVA component decreased and the change of its crystalline structure occurred due to the scission and degradation of PVA macromolecular chains. The poor resistance of vinylon-milk fiber to wet heat originated from the heat denaturation of PVA component.Vinylon-milk fiber knitted fabric had the poor size stability; the high shrinkage of yarn and the special structure of knitted fabric are responsibility of that. There were many measures to solve the problem, In this thesis, thermosetting and disposing with glyoxal were the emphases of the paper. By comparing the bursting strength and shrinkage rate, the optimized disposal condition was obtained as following, thermosetting: temperature 120℃, time 60s, transverse and lengthways expansion rate -5%; glyoxal disposal: (CHO)₂ 30g/L, activator MgCl₂ 15g/L,treatment temperature 140℃,treatment time 150s.