Influence of Chmeical Structure of Polymide Prepolymer on Rheo-Mechanical Properties of Polyimide Foam Composites

摘要

A study is reported of the effect of vaJying chemical composition of foam polyimi< prepolymers (H-complex) on the structure and properties of foam polyimide resil and their composites with aromatic polyimide fiber felt. The melt rheological beha ior of the H-complex was found to be strongly dependent on its chemical compo~ tion and structure reorganization in the melt which is akin to mesophasic structur transition states in liquid crystal polymers. Changing the diamine part of the H-cor plex from 4,4-methylene dianiline to 1,3-diarninobenzene red to decreased stea< shear viscosity at temperatures and shear rates ranging between 95° and 105°C ar 0.01 and 1 S-I, respectively. Additionally, changing the dialkyl moiety from dilnetlJ to diethyl in 3,3.,4.4'-benzophenonetetracarbox:ylic dialkyl ester (precursor to the I complex) increased gelation time of the H-complex, enhancing processibility of tI foam polyilnide composites. The results indicate that novel, lightweight foam pol imide composites with enhanced thermomechanical properties for beneficial USI can be prepared through chemical modification of the H-complex prior to its thenn ilnidization in the presence of the aromatic polyimide fiber felt.