SEMICRYSTALLINE THERMOPLASTIC POLYIMIDE PLUS POLYMER LIQUID-CRYSTAL BLENDS - NONISOTHERMAL CALORIMETRY AND THERMOGRAVIMETRY

Blends of a thermoplastic polyimide (TPI) and a polymer liquid crystal (PLC) were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The presence of PLC enhances orienta tion in the system and lowers the crystallization temperature-a manife station of the channeling effect predicted theoretically (38). The deg radation studies show high temperature stability of all blends with th e degradation onset consistently above 520 degrees C. The onset decrea ses with PLC concentration but reaches a plateau above 30 wt% PLC when the PLC-rich islands are formed. The amount of moisture absorbed decr eases with the PLC concentration while the moisture does not affect th e degradation of the samples significantly. A phase diagram is constru cted for the PLC + TPI blends from the DSC and TGA data. A comparison of amorphous and semicrystalline TPI and the characterization of amorp hous TPI + PLC blends will be reported later.