Ultraviolet resistance modification of poly(p-phenylene-1,3,4-oxadiazole) and poly(p-phenylene terephthalamide) fibers with polyhedral oligomeric silsesquioxane

Octa-ammonium chloride salt of polyhedral oligomeric silsesquioxane (POSS) was synthesized by a hydrolysis reaction and introduced into poly(p-phenylene-1,3,4-oxadiazole) (p-POD) and poly(p-phenylene terephthalamide) (PPTA) fibers by a finishing method to enhance the UV resistance. The effects of the POSS concentration, treatment temperature, and time on the tensile strength of the fibers were investigated. The surface morphology, mechanical properties, crystallinity, degree of orientation of fibers, and intrinsic viscosity of the polymer solution were characterized in detail. The results indicate that the tensile strength retention and intrinsic viscosity retention of the fibers treated with POSS were much higher than those of the untreated fibers after the same accelerated irradiation time; this demonstrated that this treatment method was feasible. We also found that the efficacy of the protection provided by POSS was more beneficial to p-POD than PPTA because of the different structure. (C) 2015 Wiley Periodicals, Inc.