Making polyvinyl alcohol films iodinated at solution state before casting and its application

This research focused on the manufacture a polarizing film with PVA iodinated at solution before casting (IBC) film, which was prepared by casting aqueous solutions of 10 wt % poly(vinyl alcohol) (PVA) containing boric acid with 0, 0.1, 0.5, and 1.0 mol/L of I₂/KI aqueous solution, and I₂/KI(1:2) with 0, 5, and 10 wt % of PVA. The lights of wavelengths between 450 and 700 nm were polarized in UV analysis. The degree of polarization and transmittance of the IBC polarizing film (10 wt % I₂/KI and 0.5 mol/L boric acid) are 99.9% and 43.2%, respectively. The resistance of the heat and humidity of IBC polarizing films was higher than that of commercial polarizing films, which were elucidated by changing the transmittance of the films. This can be explained by the fact that the interaction between polyiodine molecules and PVA chains as the state of IBC is higher than that of the commercial state. The effect of boric acid may be strengthened for the resistance of heat and humidity. Crosslinking by boric acid improved thermal properties of the IBC polarizing films, resulting from the increases of degradation temperature in DSC and TG analysis. And the unit cell broadening occurred, which was caused by the intrusion of boric acid into PVA chains in X-ray analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008