Thermal expansivity and thermal conductivity of amorphous thermoplastic polyimide acid polymer liquid crystal blends

Linear thermal expansivities alpha(L),and thermal conductivities of polyimide (TPI) and polymer liquid crystal (PLC) blends were studied. The glass transition temperatures T-g of our amorphous TPI and the PLC are, respectively, 240 and 220 degrees C. The addition of the PLC induces orientation through the channeling process, as predicted by an extension of the Flory statistical-mechanical theory of PLCs (27). Channeling was observed at PLC concentrations as low as 5 wt%. Thermal conductivity decreases with the addition of the PLC to the TPI. The anisotropic expansivity of the blends shows a strong dependence on PLC concentration and orientation direction. The pure PLC shows a maximum on the along-the-flow expansivity vs, temperature curves and also negative alpha(L) values. TPI addition moves the expansivities to positive values, but the maximum persists, even for 5% PLC only.