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.