Journal of Applied Polymer Science, Vol.63, No.9, 1113-1126, 1997
Effect of Cure Conditions on Probimide-32 Polyamide-Imide
We report on a curing study of Probimide 32, a preimidized polyamide-imide. The polymer was in a solution of N-methyl pyrrolidone (NMP) and xylene and was spun cast or doctor-bladed to form films for study. The films were cured by drying under a variety of conditions to effect solvent removal. We characterized the effects of cure by thermogravimetric analysis, dynamic mechanical analysis, Fourier transform infrared spectroscopy, and differential scanning calorimetry. Index of refraction was measured by waveguide prism coupling. Although the polymer did not require postprocessing thermal closure of its imide group, the physiochemical makeup of the system, and consequently, the properties of the Probimide 32 films, were highly dependent upon the curing temperature and environment. The properties/thermal stability improved as residual solvent was driven from the films. In the films hard baked at 300 degrees C, the extent of thermally induced crosslinking was substantially greater in air-cured films than in nitrogen-cured films. The crosslinking markedly affected the properties and relaxation behavior of the material.