POLYAMIC ACIDS - THERMAL AND MICROWAVE IMIDIZATION AND FILM PROPERTIES

Polyamic acids were synthesized from benzophenonetetracarboxylic dianhydride and diamines, viz., 4,4'-diaminodiphenyl methane and 4,4'-diaminodiphenyl ether, The course of imidization of the polyamic acids both by thermal and microwave treatments was tracked by infrared spectroscopy. The mechanical properties, namely the tensile strength and toughness of the films of polyimides with varying degree of imidization obtained by the two treatments were compared. The effect of degree of imidization of polyimide coatings on adhesion to copper substrate was also studied. Nearly 100% imidization was achieved by the thermal process, whereas the maximum imidization that could be achieved by the microwave process was about 50%. In thermal imidization, the adhesion values of the coatings slowly increased, attaining a maximum value at 80% imidization, after which there was a decrease in adhesion. (C) 1993 John Wiley & Sons, Inc.