Initial Study On The Deterioration And Consolidation Mechanism Of Fragile Wool Textiles

The silk road promoted the cultural communication between the east and west in the history.Xinjiang region was an important route in the history silk road, and large amounts of beautifulancient wool textiles was excavated. Ancient wool textiles became fragile and vulnerable aftersuffering from complicated factors of temperature, groundwater and salts due to thecharacteristic continental climate. The investigation of deterioration and consolidationmechanism is urgent to better preserve and display of wool textiles.Heat and moisture ageing method and heat and moisture ageing combined with salt methodwere chosen to simulate ancient wool textiles through characterization of the ancient wooltextiles excavated from Xiaohe Cemetery. The deterioration mechanism was also investigatedaccording to the ageing process of wool textiles. The consolidation system of aminoacid/glutaraldehyde (GA) was applied in the consolidation of fragile wool textiles. Meanwhile,consolidation mechanism was initial studied by comparing keratin/GA and keratin/Ethyleneglycol diglycidyl ether (EGDE). The conclusions are listed as follows:A large amount of salts and soil covering on the fiber surface, longitudinal fracture andmicropores of cross section appearing, scales, cortical layers, disulfide bonds, and thermalproperties significantly damaging result in rot of ancient wool textiles. The morphologies resultsshow that the aged wool textiles, especially for that obtained by heat and moisture ageingcombined with salt method is similar to ancient wool textiles. The Fourier transform infraredspectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and aminoacid analysis (AAA) results indicate that the content of cystine, thermal stability and crystallinityof wool significantly decrease. The heat and moisture ageing combined with salts method isproper to simulate the condition that ancient wool textiles existed. It indicates that salts play animportant role in the degradation of wool textiles.The optimum condition of consolidation with GA was determined by the orthogonalexperiment. The breaking stress and strain of consolidation sample obtains2.62and3.44timesincreasing under the condition of which the concentration of GA, the immersing time and the temperature are1%,1h and30℃, respectively. The organic solvent is not appropriate and the pHof GA solution has no significant effect on improving the properties of fragile wool textiles. Theconcentration of alanine solution and GA solution, the immersing time in alanine solution andGA solution are2%,1%,90min and60min in alanine/GA consolidation system. Theconcentration of histidine solution and GA solution, the immersing time in histidine solution andGA solution are1%,1%,30min and30min in histidine/GA consolidation system. Theconcentration of glycine solution and GA solution, the immersing time in glycine solution andGA solution are1%,1%,30min and30min in glycine/GA consolidation system. Theconcentration of cystine solution and GA solution, the immersing time in cystine solution andGA solution are0.5%,1%,60min and60min in cystine/GA consolidation system. Theconsolidation systems improve the breaking stress and strain of fragile textiles are3.50,2.11,2.61,3.20times and14.65,14.57,10.65,21.22times. The TGA, FT-IR and XRD results showthat the thermal properties of fragile wool textiles get improved and the crystallinity slightlydecrease. It indicates that GAhas join in the reaction with wool fiber.The scanning electron microscopy (SEM) and static contact angle results show that proteinfilm covering on fiber surface of fragile wool textiles after treated with keratin/GA andkeratin/EGDE consolidation system. The breaking stress and strain increased3.44,1.75timesand6.63,4.63times, respectively. FT-IR, XRD and13C NMR results show that GA and EGDEreally react with wool fiber and the thermal properties significantly improves after treated. Theconsolidation effect of keratin/GA consolidation system is better than that of keratin/EGDE. Theconsolidation mechanism was also proposed as follow: First, crosslinker directly reacts withshort distance molecular chains. Second, crosslinker reacts with long distance molecular chainsthrough keratin. Third, the protein film obtained from crosslinking of keratin covering on thefiber surface. Forth, hydrogen bond derivates from formation of keratin with inside of wool fiber.