Development of UV Protective Polymeric Layer for High Performance Fibers

Abstract

High performance fibers are characterized by their high strength to weight ratio, high thermal resistance and high chemical stability, which make them suitable materials for composite structures in planetary Venus balloons, competitive sail fabrics, soft and hard body armor, bulletproof vests, as well as, tendons for super pressure scientific balloons. High performance fibers, however, degrade upon exposure to Ultraviolet-Visible (UV-VIS) radiations. The objective of this research is to develop a polymeric protective layer to improve the UV-VIS resistance of high performance fibers. Polymeric sheath from Linear Low Density Polyethylene (LDPE) matrix compounded with (a) Rutile TiO2 nano-particles, and (b) Polyone, Inc white pigment with product code CC00012837X1 were developed to protect a braid made of poly(p-phenylene-2,6-benzobisoxazole) (PBO) yarns from UVVIS radiation. The compounded LDPE with the selective UV absorber was extruded around the PBO braid. The effectiveness of shielding the PBO tendon braid from radiation effects were investigated using commercial chambers, as well as, flight tests. The results showed that LDPE compounded with 10% TiO2 as well as LDPE compounded with the white pigment achieved very good blockage for the UV-VIS light. The results of commercial exposure, as well as, flight exposure on the BLAST and CREAM missions will be presented in this paper.