FORMATION OF A HIGHLY ORDERED POLY(N,N'-BIS-PHENOXYPHENYLPYROMELLITIMIDE) POWDER USING A HIGH-PRESSURE CURING TECHNIQUE

A high-pressure curing technique was developed to help determine the e ffects of solvent presence during the thermal curing of the polyimide poly(N,N'-bis-phenoxyphenylpyromellitimide) (PMDA-ODA). A powder form of this aromatic polyimide was produced from a polyamic acid solution using the high-pressure thermal curing technique. Preliminary characte rization of the powder indicates a high degree of crystallinity with a measured density of 1.46 +/- 0.01 g/cm3 and a distinct melting point of 594-degrees-C. The addition of chemical curing agents to the polyam ic acid solution prior to thermal treatment reduced the amount of crys tallinity observed in the cured material. Molecular weight measurement s of the polyamic acid precursor and powder suggest that the high degr ee of order observed in the powder is a result of degradation during c ure. (C) 1994 John Wiley & Sons, Inc.