Research On Clean Production Process Of Silk Based On Ultrasonic Technology

Silk fiber is known as “The queen of fiber”,and it has good taking performance,biocompatibility,degradability,good mechanical properties,and dyeing properties.Traditional bathing methods for silk degumming and bleaching have problems such as long processing time,high processing temperature,and high agent concentration,which not only caused large pollution and energy consumption,but also damaged the performance and quality of silk fibers.Therefore,it is of practical significance to reduce the processing temperature and reduce the use of chemicals to maintain the good performance of silk fibers.Ultrasonics have a great prospects in silk technology because of their merit of green,environmental protection,energy saving,emission reduction,convenience and high efficiency.The heat effects,mechanical effects,and cavitation effects of ultrasonics can improve the efficiency of finishing agents,enhance the reaction effect,and improve fiber properties.The application of ultrasound in the field of silk industry is of great significance in controlling manufacturing costs,environmental protection and green development,and enhancing the competitiveness of textiles.This paper studies the effects of ultrasonic treatment of silk on the structure,surface properties,hygroscopicity,mechanical properties,secondary structure,and thermal properties of fabrics;through different treatment times,different treatment temperatures,different ultrasonic frequencies,and different types of degumming agents,the ultrasonic method comparison with the effect of water bath on degumming of silk fiber;through different treatment time,different treatment temperature,different ultrasonic frequency,different concentrations of bleaching agent,explore the comparison of ultrasonic and water bath method on the bleaching effect of silk fabric;consider the effect of water temperature on sound speed The factors of surface tension and water saturation vapor pressure were used to simulate the movement of ultrasonic cavitation bubbles using Matlab to investigate the effect of ultrasonic frequency on thedifference in cleaning effect.The main research contents and conclusions are as follows:(1)We use different frequencies(40 k Hz and 80 k Hz)ultrasonic and bathing methods to treat silk fibers at different times(15min,30 min,60min and 90min),and we also study the effect of ultrasound on silk fiber properties.The results of moisture regain test and capillary efficiency test show that ultrasonic treatment improves the hygroscopicity of silk fibers.XPS and EDS results show that the increase in hygroscopicity is mainly due to the increase of oxygen groups and oxygen content on the fiber surface.Tensile strength results breaking strength of the ultrasonic treated silk fiber was enhanced,and the breaking elongation was reduced.The warp and weft density test,infrared spectrum and Raman spectrum showed that the increase in strength was due to the increase in the proportion of ?-sheet structure and the increase in warp density in the fiber The reduction in elongation at break is due to the decrease in random crimp structure and the increase in weft density in the fiber.The effect of ultrasonic treatment on the XRD test surface on the crystal form and crystal structure of silk fibers is negligible.Scanning electron microscope test,bending test and square meter weight test show that ultrasonic treatment of silk does not damage the surface morphology of the fiber,and it has almost no effect on the flexural modulus of silk.The cavitation bubbles generated by ultrasound will affect the tissue structure of silk fabric.It is a long time processing and an ultrasonic frequency of 40 k Hz,which makes the arrangement of the fibers in the yarn become scattered,but the impact on the square weight of the fabric is small.TGA,DSC and DTG test shows that ultrasonic treatment will increase the thermal stability of silk fibers,which may be due to the effect of ultrasonic waves to rearrange the macromolecules in the fiber to form a more compact structure.(2)We compare the degumming by ultrasonic method and water bath method,and study the ultrasonic frequency(40 k Hz,60 k Hz,80 k Hz and 100 k Hz),degumming temperature(60 ? and 90 ?),degumming time(30min and 60min),degumming agent Effects of species(citric acid,sodium carbonate and papain)on the degumming effect of silk fibers.The results of the degumming rate test showed that the degumming rate of silk increased with the decrease of the ultrasonic frequency and the degumming time.At a temperature of 60 ?,the degumming rate of the ultrasound at 80 k Hz,100 k Hz and the control group is significantly lower than that of the ultrasound at 40 k Hz and 60 k Hz.At a temperature of 90 ?,the degumming rate of the control group is above 15%.The degumming rate varies greatly with different frequencies.The degumming rate of papain was significantly higher than that of citric acid and sodium carbonate,and thehighest degumming rate was ultrasonic 40 k Hz,60 min,60 ? and 40 k Hz,60 min,90?.Infrared spectroscopy and XRD test structures show that ultrasonic silk degumming will not significantly affect the secondary structure of silk.The strength test showed that the ultrasonics had less effect on the strength of degummed silk,and the elongation at break increased compared with the control group,which may be due to the complete removal of sericin on the surface of silk fibroin during ultrasonic treatment.The whiteness index test shows that ultrasonic degumming increases whiteness index of silk under low temperature conditions,and ultrasonic at 40 k Hz,60 k Hz,and 100 k Hz reduce whiteness index of silk under high temperature conditions,which may be due to excessive reaction to hurt whiteness index of degummed silk.Scanning electron microscopy showed that the surface of silk fibers was smooth and clean after ultrasonic degumming,indicating that ultrasonic degumming would not damage silk fibers.(3)We compare the method of ultrasonic silk bleaching with water bath silk bleaching and study the ultrasonic frequency(40 k Hz and 80 k Hz),the bleaching temperature(50 ? and 75 ?),and the concentration of bleach hydrogen peroxide(0.1mL/100 mL,0.2 mL/100 mL,0.3 mL/100 mL,0.5 mL/100 mL,0.8 mL/100 mL,0.9mL/100 mL,1.0 mL/100 mL and 1.5 mL/100 mL)on the bleaching effect of silk fibers.The whiteness test shows that after bleaching,the whiteness of silk fabrics first increases,then remains unchanged,and then decreases: it increases in the concentration range of 0.1 mL/100 mL to 0.5 mL/100 mL,and the concentration range of 0.5mL/100 mL to 1 mL/100 mL.It remained basically unchanged,and the whiteness decreased at a concentration of 1.5 mL/100 mL.Under low-concentration hydrogen peroxide bleaching conditions(0.1 mL/100 mL to 0.5 mL/100 mL),the whiteness index of bleached silk in the ultrasonic group was significantly higher than that of the control group,and as the bleaching temperature increased,the whiteness index of bleached silk in the ultrasonic group was different from the control becoming more significant.Ultrasound frequency also has a greater impact on silk bleaching effect.The whiteness index of silk bleached by ultrasonics with 40 k Hz is higher than that of 80 k Hz.The XRD test showed that ultrasonics did not change the crystal structure of silk fiber after bleaching.(4)We analyze the results of the ultrasonic cavitation bubble radius motion to analyze the reasons for the difference in cleaning effect at different ultrasonic frequencies.Tested and recorded the change of water temperature with time under different frequencies of ultrasonic irradiation of deionized water.Taking into accountfactors such as the speed of sound propagating in water,water surface tension,and water saturation vapor pressure,the simulation of radial motion in the cavitation bubble period was performed.The lower the frequency,the greater the number of bubbles and the larger the bubble burst radius.The area encompassed by the radius change curve and the time axis is defined as the cavitation bubble to perform work.The research found that the ultrasonic frequency 40 k Hz has the largest work,and the ultrasonic 60 k Hz and ultrasonic 80 k Hz have little difference both equaled to 80% of 40 k Hz.Analysis of the reasons for the difference in cleaning caused by the ultrasonic frequency found that the good cleaning effect of ultrasonic 40 k Hz is due to the large number of cavitation bubbles generated by the ultrasonics,the large energy and the more work,and the good cleaning effect of ultrasonic 80 k Hz is due to the smaller bubble radius,which is easy to cracks near the surface of the soil produce an impact to accelerate the peeling of the soil.