Studies The Pre-treatment Impact On The Weight Gaining And Properties Of Silk Fabric

Silk weight gaining by graft copolymerization is mostly carried out in water solution. However, resulting from the limited swelling degree of silk fiber by water, the weight gaining ratio is always kept in a low range. In this thesis, the silk was firstly treated by the pre-swelling treatment before graft copolymerization, intending to enhance the weight gaining efficiency.Three different swelling agents were evaluated in this thesis, which were ethylenediaminete traacetic acid disodium salt (EDTA), ethylenediaminete traacetic acid disodium salt / urea (EDTA/Urea) and calcium chloride anhydrous / ethanol (CaCl₂/CH₃CH₂OH). Then, their effects on the physical properties, as well as the weight gaining of the pre-treated silk were studied,and the physiochemical and dyeing properties were investigated of the graft copolymerization after the pre-treated silk.It was found that the silk fiber diameter increased by 19.3% in the presence of 1.0% EDTA and 10.0% urea. At the meantime, the strength of the silk fabric decreased less,the popbar up graded.Then the graft copolymerization was implemented since the feeding of methacrylamide (MAA) and potassium persulfate (KPS), whose concentrations were 0.235 mol/L and 3.946×10^-3 mol/L. The copolymerization process was lasted for 60 min at 80 oC, where the pH and the bath ratio were 3 and 1:40. Compared with the fabric without pre-treatment, the weigh gaining ratio increased by 26.4%,and the strength remained the same. The further studies show that the retarded enhances 18.9%,moisture regain up-grading 20.4%. Combined with the silk weight gaining and properties, choosed EDTA/Urea to swelling the silk fiber.SEM images showed that the pretreated silk fibers appeared longitudinal stripe morphology, the cross section increased larger, microporous could be easily detected, sub-fibers were found for the silk fibers after copolymerization. The peak centered at 1743cm-1 came into being in the FTIR spectrum of the grafted silk, which ascribed to the stretching vibration of c=o group in MAA. The XRD and TG analysis demonstrated that the backbone of the silk fibers was hardly destroyed during the grafting process, and copolymer polymerization mainly occurred in the amorphous region. Furthermore, the thermal stability was enhanced after graft copolymerization. The dyeing properties of the silk after weight gaining were also studied. It was found that the dyeing properties remained the same when the weighten gaining is less than 50% by the dyes C.I. Reactive Red 194 and C.I. Acid Red 138. However, when the weight gaining exceded 50%, a minor deduction in the K/S and rubbing fastness occurred to the acid dyes. A better result was found for the fibers dyed with C.I. Reactive Red 194 that the rubbing fastness was turned out to be a high grade.