Effect of hydrolysis degree and mass molecular weight on the structure and properties of PVA films

In this work, we aim to analyze the variation of structural, thermal, and dielectric properties of polyvinyl alcohol (PVA) films by varying the molecular weight (Mw) and the hydrolysis degree (HD). The XRD study revealed the improvement of the crystallinity degree by the increase of HD or the decrease of Mw. The DSC study showed the decrease of the molecular mobility with the increase of either the hydrolysis degree or the molecular weight. The dielectric measurements showed four dielectric processes attributed to electrode/sample polarization, α a-relaxation, α c-relaxation, and β-relaxation. The activation energy attributed to α a-relaxation and α c-relaxation, increase with the increase of the molecular weight Mw, and the decrease of HD. The Ac conductivity is well fitted to the universal Jonsher law in the frequency range where the electrode/sample polarization can be neglected.