The present invention relates to a method of treating Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber to reduce the effects of heat and moisture on the fiber.
Poly(p-phenylene-2,6-benzobisoxazole) (PBO) fiber is a high strength and high modulus fiber. However, PBO fiber degrades rapidly when exposed to moisture and heat. Methods of modifying the surface of PBO fibers have previously been developed. For example, Chinese Patent Document No. CN 101235590 discloses dipping the PBO fiber into a chemical solution and then ultrasonically treating the fiber to modify the surface of the fiber. However, there is a further need for a method of reducing the detrimental effects of moisture and heat on PBO fibers.
Elimination or reduction of the detrimental effects on PBO fiber caused by exposure to moisture and heat would provide a stable high performance fiber that may be used in lightweight armor systems. Improvements in the mechanical properties of PBO fibers through secondary chemical process modifications of base level fibers, would allow for a treated and improved PBO fiber that can be incorporated into lightweight soft armor systems and Fiber Reinforced Plastics (FRPs) for combat helmets and backings to ceramic for small arms protection.