Thermal Characterization of New High Performance Semi-Interpenetrating Polymer Networks

摘要

Thermosetting and thermoplastic polyimides have complementary physical/mechanical properties. While thermosetting polyimides are generally easier to process but more brittle, thermoplastic polyimides are harder to process but tougher. A combination of these two types of polyimides may help produce polymers more suitable for aerospace and other non-aerospace applications that require both easy processing and good tougness. Semi-interpenetrating polymer networks (semi-IPN's) of thermoset LARC~TM-RP 46 and thermoplastic LARC~TM-IA poolyimides were prepared in weight percent ratios ranging from 100:0 to 0:100. Thermal analysis and dynamic mechanical nalaysis were made on these samples to correlate their chemcial composition with physical/mechanical/morphological properties. As expected, the glass transition temperature increases with an increase in thermoset concentrations. The opposite is true for the thermo-oxidative stability. All the semi-IPN's showed unusually good phase-mixing. The resin density goes through a maximum at about 50:50 weight ratio. Suggesting that the semi-PN samples are not merely a solid solution of the two polymeric components. This non-linear behavior may be interpreted in terms of the existence of an electrostatic interaction betwene the two constituent polymers.