SYNTHESIS AND PROPERTIES OF POLY(ARYLENE ETHER BENZIMIDAZOLE)S

Poly(arylene ether benzimidazole)s were prepared by the aromatic nucleophilic displacement reaction of three new bis[(4-hydroxyphenyl)benzimidazole] compounds with activated aromatic difluoro compounds in N,N-dimethylacetamide at 155-degrees-C in the presence of anhydrous potassium carbonate. The polymers exhibited glass transition temperatures ranging from 264 to 352-degrees-C and inherent viscosities from 0.79 to 1.99 dl g-1. Unoriented thin films exhibited tensile strengths, moduli and elongations at break at 23-degrees-C of 121 157 MPa, 3.7-4.5 GPa and 6-18%, respectively. In most cases the films exhibited 50-60% retention of 23-degrees-C tensile properties when tested at 232-degrees-C. Based on preliminary evaluation, one polymer was prepared at several different controlled molecular weights and end-capped with a monofunctional benzimidazole compound. The polymer with a calculated number-average molecular weight of approximately 9700 g mol-1 exhibited improved processability without significantly reducing thin-film properties. Composite specimens fabricated at 360-degrees-C under 1.4 MPa for 1 h exhibited good flexural and compressive propeties at 23-degrees-C and excellent retention of flexural strength and modulus at 232-degrees-C.