Property investigation for high-Performance Polyimides fabricated via compression molding in solid-like state

Abstract

A compacted body was fabricated by pulverulent polyimide (PI) block copolymers using solid-like state compression molding (SCM) technique. Polymer heated to solid-like state, i.e. the high-elastic non-melting state above the glass transition temperature (Tg) and well below melting temperature, could achieve plasticity due to dramatic decreases in elastic modulus. Tensile properties were taken as response values, and the results of single-factor experiments indicated that molding temperature was the dominant parameter on mechanical performances, followed by molding pressure and holding time. Within this context, the SCM process possesses a longer processing time window whereas the processing temperature is narrow. The manufacturing defects induced by inappropriate processing conditions also hurt the tribological performance of PIs. Particles in a solid-like state could coalesce tightly only by exerting both high temperature and pressure in the SCM process. Thermoforming mechanism examined by atomic-scale molecular dynamics simulation indicated that non-bonding interaction forces, especially van der Waals forces play a key role in fusing among polymeric particles. This study is devoted to establishing the interdependence of structure-formability-property for high-temperature polymers that are not melt processible.