Reactive end-group polybenzimidazoles for high temperature thermosets

Abstract

Polybenzimidazoles (PBI) are heterocyclic polymers that possess high thermal and oxidative stability. The inherent strength and chemical and thermal stability of PBI make it ideal for use in extreme environments, however, the current processing of PBI molded parts makes the process practically and economically unfavorable. This work explores the improvement of PBI processability using a reactive oligomer approach. An easily processable PBI resin was synthesized, characterized, and tested in molding studies. The resin consists of PBI oligomers containing the p,p-OPBI chemistry (-O- linkage) with reactive end groups that crosslink at high temperature. The use of oligomers decreases the melt processing temperature of PBI, allowing for processability in less extreme conditions. The addition of reactive end groups allows for crosslinking during a post molding thermal cure, which imparts the high mechanical properties associated with PBI. The p,p-OPBI molded and cured articles exhibited tensile strengths of greater than 60 MPa, decreased water uptake and possessed high chemical and thermal stability.