Synthesis of novel polyimides for the testing of structure-processing and property relations when used to form high temperature polymer matrices

Abstract

High-performance polymers have found an extreme range of applications in the aerospace industry. Composites which have polymers incorporated in them can usually meet the needs of the design, and are the ideal materials for aerospace applications due to their light weight, high strength, and radar transparency. Phenyl-ethynyl terminated oligomers, for example, have found many uses in the aerospace industry. Phenyl-ethynyl terminated oligomers (AFR-PEPA-N) exhibit glass-transition temperatures of up to 450°C. Unfortunately crystals form due to interactions of the oligomers. These crystals do not melt until 360°C after 15 minutes when the resin is already 50% cured. Investigation was performed to find any possible alteration to the end-caps and monomer chain elements of the current AFR-PEPA-N. Several siloxane related amines were added to the AFR-PEPA-N chain to form protective coatings when in service at high temperatures. The new poly(siloxane imide) showed an increase in processability while mantaining AFR-PEPA-N properties. In addition, phenyl-ethnyl end-caps were substituted with an ethynyl end-caps which showed no improvement in processability.