Physical characteristics of silk fibers modified with dibasic acid anhydrides

Abstract

SYNOPSISThe objective of this study was to investigate the physical properties of silk fibers modified with dibasic acid anhydrides. These are potentially attractive modifying agents to reduce the rate of photoyellowing of silk during and following UV irradiation. Several analytical techniques were employed, which included the measurement of the basic mechanical properties (tensile strength and elongation at break), equilibrium regain, amino acid analysis, dynamic viscoelastic measurements, X-ray diffractometry, and scanning electron microscopy (SEM) . The succinylated silk fibers, which have been conditioned under different relative humidity atmospheres, always exhibited slightly higher equilibrium regain values than those of equivalently conditioned glutarylated silks. The amount of the basic amino acid residues slightly decreased following modification with both succinic and glutaric anhydrides. The birefringence values and the isotropic refractive indices decreased only slightly, which suggests that the fine structure of the treated silk fibers was not significantly altered. The X-ray diffraction curves demonstrated that no changes in the crystalline structure were induced by reaction with dibasic acid anhydrides. The tensile properties of the modified silks remained more or less unchanged. Only the initial tensile resistance of glutarylated silks in the dry state significantly decreased. The dynamic viscoelastic behavior of modified silk fibers was characterized by a reduced thermal stability. In fact, the onset temperature of the prominent E peak corresponding to the molecular movement shifted to lower values.The surfaces of modified silk fibers were as smooth as that of the untreated control sample.

Absorption of metal cations by modifiedB. mori silk and preparation of fabrics with antimicrobial activity

“…Higher extents of acylation were attained by using other aliphatic acid anhydrides, such as succinic and glutaric anhydrides. 15 On the basis of the kinetic data shown in Figure 1, samples of silk fabrics modified with TA or acylated with EDTA-dianhydride with similar weight gains (5, 12, and 17%) were prepared for the metal uptake tests.…”

Grafting of methyl methacrylate (MMA) onto Antheraea assama silk fiber

“…Investigationshave been carried out by many workers for improving some of the inferior performance properties of silk such as photoyellowing, wrinkle recovery, abrasion resistance, and wash and wear by adopting various graft copolymerization and/or chemical‐modification techniques 1, 2. Epoxides,3 glutaraldehyde,4 glycol diglycidyl ether,5 and aliphatic and aromatic dibasic acid anhydrides6, 7 have been used for chemical modification of silk and wool 8. Graft copolymerization as such has become an attractive means of chemical modification of protein fibers, since such treatments, in general, improve some of the disadvantages associated with these fibers 9, 10.…”

Changes in physical properties of methacrylonitrile (MAN)‐grafted silk fibers

“…Moreover, the acylation with dibasic acid anhydrides appeared particularly attractive, because a slight chemical modification resulted in a significant change of the dyeing properties of silk and other animal protein fibem6y7 We studied the physical properties and the thermal behavior of silk fibers, modified by acylation, and found that dibasic acid anhydrides were reactive mainly towards basic amino acid residues. 8 Several vinyl monomers, such as methyl methacrylate (MMA) ,' methacrylamide (MAA) ,lo 2-hydroxy-ethyl methacrylate ( HEMA), " ethoxy-ethyl metacrylate ( ETMA) , l2 methacrylonitrile (MAN), l3 and styrene (St) l4 have been used as grafting agents, and some of them were successfully applied on the industrial scale for silk processing, that is, silk grafted with MAA. The physical and mechanical properties, as well as the' structural characteristics, of silk fibers, grafted with different vinyl monomers, have been reported.…”