Melt‐processable oligoamides having internal acetylene groups in the backbone, and thermally stable polyamides therefrom

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Abstract
Aromatic oligoamides of DP = 5 and 11 that have all meta‐phenylene linkages were prepared by controlling the ratio of isophthaloyl chloride and diamines [m‐phenylenediamine and bis(3‐aminophenyl)acetylene], and then end‐capped with aniline or 2‐aminobiphenylene. Aromatic oligoamides having para‐phenylene linkages were also prepared similarly using terephthaloyl chloride as a monomer. The oligoamides that have all m‐phenylene linkages were soluble in organic solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide, though the oligoamides having p‐phenylene linkages were much less soluble. The oligoamides having acetylene units in the backbone showed exotherm due to crosslinking. The onset of the exotherm appeared at 310‐340°C for the oligoamides having all m‐phenylene linkages, and 330‐370°C for the oligoamides having p‐phenylene linkages. They were melt‐processed at 350 or 380°C for 1 h, giving tough and insoluble films from oligoamides having all m‐phenylene linkages and brittle films from oligoamides having p‐phenylene linkages. The films showed excellent thermal properties. For example, viscoelastic analyses showed little decrease of mechanical property up to 370°C, and Tg was not observed below the temperature. Thermogravimetric analyses also showed that thermal stability of the melt‐processed films were excellent. © 1992 John Wiley & Sons, Inc.