Balance of chemical and physico-chemical transformations in solutions of polyamic acids on storage

A kinetic study has been made of the degradation of polyamic acid, viz. a product of the polycondensation of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether (PAA-PM) in dimethylformamide solutions. The degradation rate constants have been calculated at several temperatures, including room te...

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Bibliographic Details
Published in:Polymer science USSR 1981, Vol.23 (6), p.1406-1413
Main Authors: Bel'nikevich, N.G., Denisov, V.M., Korzhavin, L.N., Frenkel, S.Ya
Format: Article
Language:English
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Summary:A kinetic study has been made of the degradation of polyamic acid, viz. a product of the polycondensation of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether (PAA-PM) in dimethylformamide solutions. The degradation rate constants have been calculated at several temperatures, including room temperature. The hydrolysis rate constants were obtained at different water/amide groups ratios up to a tenfold excess of water. The results obtained point to an absence of direct hydrolytic splitting of PAA-PM. The rate constants of imidization in 13·5% solutions of PAA-PM in DMF were calculated from the PMR spectra at temperatures up to 120°. The balance of imidization and degradation reactions was evaluated at moderate temperatures.
ISSN:0032-3950
1878-268X
DOI:10.1016/0032-3950(81)90107-6