Preparation of Syndiotacticity-Rich High Molecular Weight Poly(vinyl alcohol)/Iodine Polarizing Film with High Water Resistance

摘要

To enhance durability of poly(vinyl alco-hol) (PVA)/iodine polarizing film under humid and warmatmospheres and to identify the effects of syndiotacticityon the polarizing efficiency (PE) and durability of PVA/iodine complex film, we prepared three high molecularweight (PVA)s with similar number-average degree of po-lymerization (Pa) of 4000 and with different syndiotacticdiad (s-diad) contents of 53, 56, and 59%, respectively. Itwas found that syndiotacticity of PVA had a significantinfluence on the durability of PVA /iodine complex film inwarm and humidity conditions (relative humidity of 80%and temperature of 50°C). That is, both desorption ofiodine in PVA/iodine film and transmittance of film decreased with increasing syndiotacticity of PVA. In thecase of PE, the values of over 99% were obtained at eachoptimum conditions. The change of PE (durability) ofPVA/iodine complex films having P_nof 4000 and s-diadcontents of 56 and 59%, respectively, in warm and humid-ity conditions was almost zero, whereas those of PVA/iodine film with s-diad content of 53% and with (P_n )sof1700 and 4000 were about 60% and 50%, respectively,under same conditions.