Influence of urea on polarization property and mechanical properties of polyvinyl alcohol films for the polarizers

Poly (vinyl alcohol) (PVA) is an ideal material for preparing the polarizing film because of its excellent transparency and dying properties. In the present work, urea was used to act as a PVA plasticizer to modify the crystallization behavior by controlling the intensity of the intermolecular hydrogen bond. The results had shown that the incorporation of the plasticizer decreased the crystallinity and the melting point of PVA. The mechanical property such as elongation had greatly improved to 383.23 ± 20.31% at 3wt% of the Urea. The FTIR absorption peaks of Urea-modified PVA film stain samples were the same as those of PVA film stain samples. The morphology analysis was carried by SEM and element mapping which indicated that except for the surface, urea was uniformly dispersed in the PVA matrix. From the DSC, Raman, and XRD test, the decrease of crystallinity after the addition of urea was conducive to the absorption of iodine and the formation of a polyvinyl alcohol-iodine complex. The intensity of absorption peak in the Raman spectrum increased, and the polarization performance of the films was improved.