Abstract
Polybenzimidazoles are heterocyclic polymers which are known for their outstanding thermal and chemical stability. Hoechst Celanese has recently developed PBI (2,2'-(m-phenylene)-5,5'-bibenzimidazole) as an engineering plastic with the trade name Celazole. The polymer has excellent compressive strength, high tensile strength and modulus, and a glass transition temperature of 453°C (P. A. Steiner and R. B. Sandor, High Perf. Polym., 3, 139 (1991)). Low molecular weight, oligomeric forms of PBI have been used in the past as a composite matrix material to produce stiff and boardy prepregs. More recently medium molecular weight PBI (12 000-20 000 weight average) has been used in combination with N,N-dimethylacetamide (DMAc) solvent to produce prepregs with excellent tack and drape. These prepregs have significantly reduced condensation by-products resulting in improved processability and properties. Reported herein are composite mechanical properties on the low molecular weight PBI prepregs illustrating their improved performance and processability.
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