Diffusion and Copolymerization of Polyacrylic Acid in Nylon 66 Fibers to Achieve Improved Thermal Protection and Higher Moisture Regain

摘要

An increase in the moisture absorption and melting temperature of nylon 66 is desirable for improving garment comfort and thermal resistance of nylon textile material. Grafting of acrylic acid monomer to nylon by various techniques has been intensively investigated for these purposes and also for potential protection against toxic agents. However, the possibility of copolymerizing polyacrylic acid (PAA) homopolymer to nylon appears to have been by-passed or considered unfeasible by other workers. The report describes the copolymerization or fixation of a relatively low molecular weight PAA to nylon by a heat cure reaction. PAA homopolymer with a molecular weight of 15,000 to 20,000 was selected and applied to a spun nylon 66 fabric from an aqueous solution containing 28 percent polyacrylic acid by weight. Thermal analysis showed a complete loss of the nylon 66 melting point endotherm and instead showed a strong endotherm at 337C. and a moderate endotherm at 230C. A reaction between the terminal amine groups of nylon 66 and carboxyl groups of PAA forming an amide linkage was concluded to be partially responsible for the fixation. This suggested that a block copolymer and perhaps a graft copolymer were obtained. The calcium salt form increased the melting temperature of the nylon to over 385C. (Author)