Research On The Silk-reeling Process To Improve The Stability Of Fresh Cocoon Raw Silk Cohesion

Compared to the dried cocoon silk reeling process,fresh cocoon silk reeling process saves the drying process of cocoons.It can shorten the process,save time,make the best of by-products and earn extra profits.So fresh cocoon silk reeling technology has a booming market.However,because of the instability of sericin,the fresh cocoon raw silk have poorer cohesion and neatness than the dried cocoon raw silk,which will narrow its scope and cannot satisfy the requirement of the high grade product.Therefore,it is necessary to adjust the silk reeling process in order to obtain high quality fresh cocoon raw silk.The main reason for the differences between them is the cohesion.Improving the cohesion(including raw silk cohesive force and its stability)depends on the sericin.This paper explores the impact of heat-moisture treatment,microwave pretreatment and chemical reagents on the properties of raw silk,by researches on the properties of sericin.The experiment is divided into three parts: The first part is to discuss the effects of heat-moisture treatment.We select the dried cocoon and fresh cocoon,use vacuuming penetration,cocoon cooking(non cocoon cooking)and multi-end silk reeling to produce raw silk(30/33D).The second part is talking about the influence of microwave pretreatment.We use microwave pretreatment with different time before silk reeling.The third part is to investigate the impact of chemical reagents.We add a device to the multi-end reeling machine.The strips can be coated with different concentration of glutaraldehyde solution when passing the device.Then soak the raw silk according to weaving requirements by HC and EKL-200.Finally,test their performance to judge them,including morphology test,cohesion test,crystallinity test,orientation test and mechanical property test,which can offer valuable suggestions for setting reeling process.The results show that:(1)The breaking strengths of the dried cocoon and fresh cocoon raw silk are also beyond 3.5 cN/dtex.They have good cohesion,the average times are more than 150.So they can satisfy the basic requirement of weaving.After soaking by HC,the cohesion of dried cocoon raw silk reduces 1.3%,the fresh cocoon raw silk reduces 13.3%.After soaking by EKL-200,the cohesion of dried cocoon raw silk reduces 52.3%,the fresh cocoon raw silk reduces 77.6%.Therefore,the cohesive stability of fresh cocoon raw silk is inferior to dried cocoon raw silk.(2)When cooking cocoons before reeling process,the breaking strength of the raw silk is over 3.5 cN/dtex.Its cohesive times are beyond 110.So they can satisfy the basic requirement of weaving.After soaking by HC and EKL-200,the cohesive times are decreased by 5.0% and 68.3%.So cocoon cooking process can improve the stability of cohesion.(3)When taking microwave pretreatment before reeling process,the breaking strength of these raw silk simples are over 3.5 cN/dtex.Their cohesive times are more than 130.So they can satisfy the basic requirement of weaving.After soaking by HC,the times are over 100.After soaking by EKL-200,the cohesive times are decreased by 41.2%.So microwave pretreatment can contribute to improving the cohesion and its stability of the fresh cocoon raw silk.(4)When using glutaraldehyde treatment during reeling process,the breaking strength of these raw silk simples are over 3.5 cN/dtex.They have good cohesion,the average times are beyond 125.The times are over 100 after soaking by HC.After soaking by EKL-200,the cohesive times are decreased by 43.3%.It means that glutaraldehyde treatment can help to strengthen the cohesion and its stability of the fresh cocoon raw silk.(5)After the microwave pretreatment,heat-moisture treatment and glutaraldehyde treatment,these fresh cocoon raw silk simples have good mechanical property and their breaking strength are over 3.5 c N/dtex.The average times of their cohesion are beyond 130.After soaking by HC,all the descending range of the cohesion times are below 10%.After soaking by EKL-200,the cohesion of the raw silk under complex process are superior to the raw silk under single process.Thus,we can design the silk reeling process with the combination of three treatments,which will be more able to the improvement of cohesion.(6)The curve shapes of their crystallinity are similar and their orientation range from 0.85 to 0.95.So the main effect of three treatments is sericin.They have virtually no effect on the fibroin.The results show that after adjusting the silk reeling process by heat-moisture treatment,microwave pretreatment and glutaraldehyde treatment,the cohesion and its stability of fresh cocoon raw silk can be improved.So we can expect to solve weaving problems and obtain high quality fresh cocoon raw silk by these ways.