Stabilization of Cotton Fibers during Mechanical Cutting

Abstract

The mechanical stress energy used to process cotton in a cutter is sufficient to induce homolytic scission of C₂ and C₃ bonds and chain scission of C₁—O—C₄ glycosidic bonds, i.e., to reduce the degree of polymerization (DP), of cellulose molecules. The formation of carbon and alkoxy mechanoradicals at these locations was identified by an electron spin resonance study. The incorporation of nonylated phenol phosphite, hindered amine, and milled wood lignins of red oak and white oak was effective in inhibiting the reduction of the DP of cellulose. In addition, the incorporation of an alkylary phosphite mixture, hindered phenol, ditridecyl thiodipropionate and dialutyl thiodipropionate, milled wood lignin of loblolly pine and white oak, and lignosulfonate of spruce and red oak was useful in inhibiting the oxidative ageing of cut cotton fiber. Of the stabilizers used, only milled wood lignin of red oak was the most effective in preventing loss of the DP of cellulose during mechanical cutting and oxidative ageing. Termination of primary mechanoradicals at C₂ and C₃ by stabilizers appeared to eliminate secondary reactions that led to a subsequent decrease in the DP. Termination of alkoxy and carbon radicals at C₄ and C₁ positions appeared to eliminate oxidative degradation.