REACTIVITY OF POLY(AMIC ACID) ISOMERS IN THERMAL IMIDIZATION

The reactivity of isomers of poly(amic acid) prepared from 4, 4′-oxydianiline and pyromellitic dianhydride in thermal imidization was investigated both in solutionand in solid state at 130°C. FT-NMR was the main tool used to measure the mole fraction of various species formedin partial imidization, using diphenyl pyromellitamic acid as a model coinpound to verify its applicability. The results were modeled by kinetic equations. It showed that the terephthalamide isomer reacted 4.14 times faster than isophthalamide isomer when imidized in solution. On the other hand, the isophthalamide isomer reacted 3.25 times faster than the terephthalamide isomer when reacted in solid state. © 1990 The Society of Polymer Science, Japan.