Study On Reshaping And Fixing Of Silk Gelatin

The natural silk is not only soft and gorgeous,but also light and elegant.It can keep body warm, release more wet,and more important,it has concinnous gloss as pearls.The silk fiber is elegant with all these characteristics.In tradition industry,the silk is refined silk whose sericin is entire removed.The sericin and fibroin are both natural proteins,and the sericin has better performance than fibroin on antibiosis,hydroscopicity and antioxidation.After refined,the silk will decrease 20-25 percent weitht because of the sericin's removal.This will induce the silk cloth less trimly and fullness,and can't get more economic returns.In process of production,lots of methods have been applied in order to increase the silk weight.However,the majority of these methods are too complicated and the reaction condition can't easy to control.Especially some methods which applied heavy metals in silk,will result in harmful effects to human body.In the process of silk refining,a kind of organic waste water which contains plenty of both N and P elements can be produced.With lots of sericin,the waste water can not only contaminate the environment,but also waste a lot of natural stock.How to effective use sericin,lower the cost of sewage disposal,and keep clean production,are requirement of recycling economy.And in present, the important topic is how to utilize sericin to resist uv-ray and bacteria in order to satisfy consumers' expectation of novelty and healthy to silk production.With the development of science and technology,the advantage of sericin has been discovered gradually.In addition,the consumers have new pursuit to silk clothes.So,the sericin's fixing become the research emphasis of this field.In the past decades,there are a lot of fixing agents which have been reported,such as aldehyde(formaldehyde,glutaraldehyde,et al.),heavy metal salts, tannin,cyanuric chloride,dichloro striazine-type reactive dyes.However,because they all have some disadvantages,there are difficulties to apply for mass production and general application.In the numerous fixing agents,through comparing,we find glutaraldehyde is a kind of excellent protein cross linking agent.It has good effect of sericin fixing.After protein cross linking,it can't cause lots of sericin losing in the process of refining.If in an eligible sericin fixing condition,only a little(0.1-5.0%)sericin can be lost in the process of refining.In addition,glutaraldehyde,which not only has low price,but also has been widely used,is a kind of immediate effect,broad spectrum, and excellent chemical antibacteria.Protein being fixed by glutaraldehyde can be used for human body reimplantation,so low concentration glutaraldehyde can't damage human body.Furthermore,ω-amino on the side chain of anino acid residue in sericin which can be used for sericin fixing,it make silk have the function of antibacterial and good for humans' health.As we all know,everything has two sides.Disadvantage also exists on sericin fixing by glutaraldehyde,that is it can make silk xanthochromia,and effect staining and using in the following.So,in order to change the xanthochromia phenomenon,the author carry out a deep research on sericin fixing by glutaraldehyde, and results as follows:1 Sericin fixing by cross linking agent GAWe perform a three factors,four levels orthogonal experiment which set temperature 0-40℃, GA concentration 0.1-1.0%,and time 1-24 hours.We analyzed the rate of inoculation,the rate of decrease in refining,and performed whiteness comparison.And results as follows:the rate of inoculation has a high number in the condition that temperature at 25℃,GA concentration 0.5%,and time 24h.In the time range of 1-24b,the rate of inoculation has a higher value when been given longer time,and temperature and time have large effect on the rate of inoculation.These three conditions,temperature,time and GA concentration,have linear relationship on the rate of decrease in refining.In a setting range,the rate of decrease in refining may step down as temperature raising, time prolongation,and GA concentration increasing.And in this study,the xanthochromia degree of silk can increase with these conditions changing larger.Furthermore,even in a low level of these conditions,the silk xanthochromia can effect its staining and utilization.2 the effect of compounding agent on GA cross linking of sericin fixing(1)Using Urea as a compounding agentWe perform a three factors,four levels orthogonal experiment which set temperature 0-40℃, GA concentration 0.1-1.0%,time 2-24 hours and Urea concentration 0.5-2.0%.We analyzed the rate of inoculation,the rate of decrease in refining,and performed whiteness comparison.And results as follows:Using Urea as a compounding agent,the effect of cross linking is good,but the rate of inoculation is lower than only using GA as fixing agent.GA concentration has significant effect on the rate of inoculation.When adding Urea,the rate of decrease in refining step down obviously,and the fastness of sericin fixing is well.Temperature and GA concentration have significant effect on the rate of decrease in refining.The whiteness of silk has a little better than only using GA as cross linking agent,but it is still not good enough. (2)Using inorganic acid as a compounding agentWe perform a four factors,four levels orthogonal experiment which set temperature 0-40℃, GA concentration 0.1-1.0%,time 1-24 hours and pH 1.5-3.0.We analyzed the rate of inoculation,the rate of decrease in refining,and performed whiteness comparison.And results as follows:Using inorganic adjusting pH,the polymerization of inter- and intramolecular of GA can be prevented.At the same GA concentration,temperature and time,the pH value is lower,the whiteness of silk is better,but the rate of inoculation and the fastness of sericin fixing may decrease when the pH value lower.pH value has significant effect on rate of inoculation.When refining the sample of sericin fixing silk,the rate of sericin losing and the rate of decrease in refining are high.Furthermore,this phenomenon is more significant when time is shorter,temperature is lower,and pH value is lower,at the GA concentration of setting in experiment.So it has not fixed the sericin tight.3 influence of other factors on sericin fixingAccording to the reaction characteristics between GA and sericin,we design this compounding by using changing the physical structure of sericin and the reaction environment of GA.The result is: the silk can't xanthochromia and the whiteness is good after sericin fixed by GA.The GA concentration can't effect on whiteness of silk.The fastness of sericin fixing is high and the rate of decrease in refining is lower.Meanwhile,we can obtain different rate of inoculation through adjusting GA concentration as we need.In the GA concentration of this study,the rate of inoculation is 1.81%(average),and the rate of decrease in refining is 0.42%(average).It is better to the rate of inoculation and the rate of decrease in refining.