Chemical modification of wool fibers with acid anhydrides

Abstract

Wool fibers were chemically modified by reaction with succinic and glutaric anhydrides. The weight gain (and acyl content) increased with increasing the reaction temperature (65-80°C) and time (1-2 h), attaining 18.9% (158.9 mol/10 5 g) and 23% (163.9 mol/10 5 g) for succinylated and glutarylated wool, respectively. Changes in the amino acidic pattern of acylated wool, i.e., decrease of basic amino acid residues and formation of ornithine, were observed by acid hydrolysis. The X-ray diffraction profiles of modified wool fibers remained essentially unchanged, suggesting that the crystalline structure was not affected by reaction with acid anhydrides. The degree of molecular orientation of acylated wool slightly decreased, especially at high weight gain. The viscoelastic response of wool modified with succinic and glutaric anhydrides was characterized by a shift to a lower temperature of both the drop of the storage modulus and the peak of the loss modulus. These features are indicative of a higher mobility of the keratin chians in the amorphous and crystalline domains. In fact, it is suggested that the chemical agent diffused into the accessible parts of ␣-crystallites, reaching the available reactive sites. This did not cause changes in the crystalline pattern of wool, but resulted in a different thermal behavior of fibers.

Wool fibres functionalised with a silane-based coupling agent for reinforced polypropylene composites

“…Silanes have versatile multifunctional structures and have been successfully applied in polymer composites reinforced with inorganic fillers [20][21][22][23][24][25][26] and natural fibres [10,15,[17][18][19]27]. Chemically modifying keratinbased fibres modifies their dye affinity, reduces felting, and improves their wettability in textile wet processing [28][29][30][31]. However, to the best of our knowledge, no articles have reported silanising wool fibres and using them to prepare polymer-based composites.…”

Grafting of methyl methacrylate onto natural keratin

“…Different studies on natural and modified wool fibers indicate that the preferred grafting sites are the thiol groups on cystine aminoacid [7,9]. However, NH and OH have also been found to act as reactive sites [11]. In Fig.…”

Keratin transamidation

“…Protein concentration was determined by spectrophotometric analysis on a Varian Cary 50 Conc UV-vis spectrophotometer using Bio-Rad Protein Assay with reference to bovine gamma globulin (BGG) (Bio-Rad Laboratories, Inc.) standard [22,23]. The protein content of solutions of solubilized keratin ranged from 5.1 mg/mL to 5.9 mg/mL.…”