Thermal and Flammability Properties of Poly(p-phenylene- benzobisoxazole)

Abstract

Poly( p-phenylene-benzobisoxazole), PBO, is a member of a family of rigid-rod, lyotropic liquid crystal polymers which can be fabricated into fiber, film and composites. PBO exhibits exceptional ignition resistance, low heat release rate, and very low smoke emission. PBO's fire, smoke, and toxicity (FST) properties are one of the best thermally stable polymers. PBO begins to ther mally decompose at 660 ° C and it has a char yield > 70% at 900 °C. It has LOI of > 56 and UL94 rating of VTM0 for 1 mil thick film. PBO generates almost no smoke, and 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. Carbon fabric/PBO composites do not ignite even after 15 minutes when exposed to a heat flux of 50 kW/m2. Preliminary results indicate that this carbon fabric/PBO composite meets the Navy's most critical fire, smoke, 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, off shore structures, and other places where the fire, smoke, toxicity properties of the material and weight are critical.