THERMAL AND FLAMMABILITY PROPERTIES OF POLY(P-PHENYLENE-BENZOBISOXAZOLE)

Poly(p-phenylene-benzobisoxazole), PBO, is a member of a family of rig id-rod, lyotropic liquid crystal polymers which can be fabricated into fiber, film and composites. PBO exhibits exceptional ignition resista nce, low heat release rate, and very low smoke emission. PBO's fire, s moke, and toxicity (FST) properties are one of the best thermally stab le polymers. PBO begins to thermally decompose at 660-degrees-C and it has a char yield > 70% at 900-degrees-C. It has LOI of > 56 and UL94 rating of VTM0 for 1 mil thick film. PBO generates almost no smoke, an d very little toxic combustion products are generated during fire. PBO is more ignition resistant and has very low heat release (measured by the Cone Calorimeter) compared to other high temperature polymers. Ca rbon fabric/PBO composites do not ignite even after 15 minutes when ex posed to a heat flux of 50 kW/m2. Preliminary results indicate that th is carbon fabric/PBO composite meets the Navy's most critical fire, sm oke, and toxicity requirements for applications inside submarines. PBO 's unique combination of thermal, mechanical, and physical properties could provide enabling technology for the next generation of products for interior components of airplanes, ships, offshore structures, and other places where the fire, smoke, toxicity properties of the materia l and weight are critical.