ON THE REVERSIBILITY OF THE CRYSTALLINE PHASE-TRANSITIONS OF POLY(PARA-XYLYLENE)

The alpha to beta of poly(p-xylylene) (PPX) was first observed for a polymer made by a Wurtz condensation of p-xylylene dichloride and also in samples prepared directly by pyrolysis of p-xylene. The authors have studied for some time and the polymerization, morphology, and thermal properties of PPX, and report that the alpha to beta //1 transition can be made reversible. This is accomplished most easily in samples annealed in the beta //2 state.