The Effect Of Papain On Mulberry Silk And Mulberry Silk Fabric

As the papain has many excellent characteristics,it can be used as ecological processing reagent in silk industry.However,there is little research on the effect of papain treatment on the performance of silk fiber and silk fabric.What's more,the cost of papain for silk degumming,modification and other processing is relatively high.These problems seriously affect the application of papain in the silk industry.Therefore,this study attempts to combine reductant and papain for silk degumming.It expects to save papain processing cost by screening reductant which can save the amount of papain and improve the degumming rate.The changes of properties of silk and silk fabric treated with papain is investigated.It enrich the related basic knowledge of the effect of biological enzyme on silk and silk fabrics.And then it will promote the application of papain in silk industry.This paper mainly study from the following four aspects.1.Enzyme activity is an important parameter of enzyme properties.In order to understand the changes of papain's activity.The activity of papain was tested by photometric method.The results showed that the activity of papain decreased during the water bath heating process at optimum temperature.Activity decreased by 50% after 3 h water bath heating at optimum temperature.Cysteine(Cys)and Na2S2O3 were added into the papain solution respectively,and the enzyme activities were 2.91 times and 1.18 times the origial respectively.The two papain solutions containing Na2S2O3 or Cys were heated in water bath at optimum temperature,and the reduction of activity of papain slow down.The activity of papain were reduced by 8.35% and 17.83% respectively after 3 h water bath.2.Since the addition of Cys or Na2S2O3 in the papain solution can improve and stabilize the papain activity,the effect of reductant on raw silk degumming with papain was further studied.Cys,Na2S2O3 and scorbic acidic three kinds of reductants were combined with papain for raw silk degumming.The results showed that the degumming rate of silk obviously increase when Cys and Na2S2O3 were added into papain solution for the silk degumming.The degumming rate of silk increase with the the mass concentration of Cysteine and Na2S2O3.When the mass concentration of Cys and Na2S2O3 reached 2 g/L and 4 g/L,The degumming rate of silk degummed with papain-reductant solution was 1.4 times and 2.2 times higher than that of papain.But the degumming rate of silk decrease when ascorbic acid and papain complex were used for silk degumming.The degumming rate of silk decrease with the increase of ascorbic acid concentration.3.In this study,silk fiber was treated with papain,and the hydrolysis to fibroin and effects of papain on the structure and the surface properties of fibrion fiber were investigated.The silk fiber was placed in 1g/L papain solution for 60 h to investigate the hydrolysis ability of papain to fibroin fiber.The hydrolysis rate of fibroin fiber reached 80%,indicating that papain has a strong hydrolytic ability to fibroin fiber.Fibroin fiber was treated with papain for a short time to investigate the effect of papain on the surface properties of fibroin fiber.In result,treated with papain in short time,the weight loss of silk fiber was less;the images of SEM showed that there are small pits on the surface of fibroin fiber when treated with low concentration papain solution,and the surface of the fibroin fiber becomes rugged and trenches appear when treated with high concentration papain solution.Papain treatment had a big damage to the strength of fibroin fiber.The strength loss increased with the concentration of papain and treatment time,the strength loss increase first and then decreased with the treatment temperature and the pH value.4.The silk fabric was treated with papain and the change of mechanical property,dyeing properties,whiteness,softness and the emerizing performance of silk fabric were investigated.In result,(1)The strength of silk fabric declined after treatment,and the strength loss increase with the concentration of papain and the time of treatment.The concentration of papain should be controlled within 1 g/L,and the treatment time should be controlled with 1 h.(2)Acidic dye was used to dye the silk fabric treated with papain and the dye-uptake rate and K/S value increase compared with control sample.The dye-uptake rate and K/S value increase with the time of papain treatment.Direct dye were used to dye the silk fabric treated with papain and the dye-uptake rate and K/S value slightly increased compared with control sample.While acidic dye and derect dye were used to dye silk fabric treated with papain for 150 min,the dye-uptake rate increased by 15.9% and 6.31% respectively,and the K/S values were increased by 0.65 and 1.15 respectively.While fabric treated with papain dyed with reactive dye the dye-uptake rate decreased slightly.(3)After papain treatment,whiteness of silk fabric did not change,and softness has improved.(5)The silk fabric treated with papain were surface abrased.Although the surface of the fabric formed a few fine fibers,but the emerizing performance is poor and need further research.