Composite porous membrane for protecting high-performance fibers from ultraviolet-visible radiation

High-strength fibers are used to produce high-strength-to-weight-ratio materials for applications such as composites, soft and hard body armor, bulletproof vests, and tendons for scientific balloons. Unfortunately, these fibers degrade when they are exposed to ultraviolet–visible (UV–vis) radiation. The objective of this research was to develop systems to improve the UV resistance of such fibers. Composite porous membranes from a polyurethane (PU) matrix loaded with rutile titanium dioxide (TiO2) nanoparticles were developed to protect a braid made of polybenzobisoxazole (PBO) yarns. The PU membranes loaded with TiO2 nanoparticles were prepared by a phase-inversion technique. The effects of the amount of TiO2 nanoparticles on the composite membrane morphological structure and UV–vis light transmission were evaluated. The results show that when the concentration of TiO2 nanoparticles was increased, the porosity of the membrane and its UV–vis blocking effectiveness increased. The UV–vis protection was evaluated by the wrapping of the PBO braid with the composite membranes and exposed to UV–vis radiation. The strength loss of the PBO fiber due to exposure was decreased from 75% for the unprotected sample to 7.8% for the protected sample in the PU loaded with 4% TiO2 nanoparticles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013