Process for controlled phase transformation of alpha phase of poly(vinylidene fluoride) to the gamma phase

摘要

Process for controlled phase transformation of powders and films of the alpha phase of poly(vinylidene fluoride) to the corresponding gamma phase. The materials prepared according to this process possess enhanced electret behavior in comparison to the more prevalent forms of this polymer commonly referred to as the alpha and beta phases. Such enhancement is achieved by impregnation of the alpha phase of poly(vinylidene fluoride) with certain phase transformation agents, followed by heating of the impregnated material in a controlled manner. The agents which have been impregnated into the polymer can later be removed subsequent to phase transformation by solvent extraction techniques. The gamma form of poly(vinylidene fluoride) prepared in the above manner can be used as electrets.