Role of molecular weight of atactic poly(vinyl alcohol) (PVA) in the polarizing efficiency of PVA/azo dye complex film with high durability

To precisely identify the effect of molecular weight of atactic poly(vinyl alcohol) (a-PVA) on the durability and polarizing efficiency (PE) of a-PVA/dye polarizing film, we prepared two (a-PVA)s with similar syndiotactic diad contents of 54.0%, degrees of saponification of 99.9%, and with different number-average degrees of polymerization [(Pn)s] of 1700 and 4000, respectively. Through a series of experiments, it was found that molecular weight of a-PVA had a significant influence on the durability of a-PVA/dye film in heat and humidity conditions (relative humidity of 80% and temperature of 90°C). That is, both desorption of dye in a-PVA/dye film and transmittance of film decreased with increasing molecular weight of PVA. The change of PE (durability) of a-PVA/dye film in heat and humidity conditions was limited to about below 5%. The change of PE of PVA/dye film having Pn of 4000 especially was limited to 1%, whereas that of a-PVA/iodine film with Pn of 4000, was almost 80% under the same condition. Also, transmittance of the drawn a-PVA/dye film was far higher than that of the undrawn one. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 967–974, 2005

[1]  K. Yamaura,et al.  Influence of molecular weight and syndiotacticity on the structure of high‐performance poly(vinyl alcohol) fibers prepared by gel spinning , 2002 .

[2]  S. Han,et al.  Modeling of the optical anisotropy of a dye polarizer , 2002 .

[3]  Byung Chul Ji,et al.  Water stability of syndiotactic poly(vinyl alcohol)/iodine complex film , 2001 .

[4]  W. Lyoo,et al.  Preparation of high molecular weight atactic poly(vinyl alcohol) by photo-induced bulk polymerization of vinyl acetate , 2001 .

[5]  S. Han,et al.  Preparation of high molecular weight poly(vinyl alcohol) with high yield using low-temperature solution polymerization of vinyl acetate , 2001 .

[6]  K. Yamaura,et al.  Gel‐spinning of partially saponificated poly(vinyl alcohol) , 2000 .

[7]  W. Lyoo,et al.  Low temperature suspension polymerization of vinyl acetate using 2,2′-azobis(2,4-dimethylvaleronitrile) for the preparation of high molecular weight poly(vinyl alcohol) with high yield , 1998 .

[8]  W. Lyoo,et al.  Structure of Poly(vinyl alcohol) Microfibrils Produced by Saponification of Copoly(vinyl pivalate/vinyl acetate) , 1998 .

[9]  W. Lyoo,et al.  Preparation of high molecular weight polyvinylalcohol by low temperature azoinitiator , 1997 .

[10]  T. Tervoort,et al.  Optical properties of oriented polymer/dye polarizers. 2. Ultimate properties , 1997 .

[11]  K. Ichimura,et al.  Surface-Selective Modification of Poly(vinyl alcohol) Films with Azobenzenes for In-Plane Alignment Photocontrol of Nematic Liquid Crystals , 1995 .

[12]  T. Nishino,et al.  Transparency and dichroism of ultra-drawn UHMW-PE films in the visible wavelength range , 1993 .

[13]  K. Miyasaka,et al.  PVA-Iodine complexes: Formation, structure, and properties , 1993 .

[14]  T. Kanamoto,et al.  Effect of molecular weight on drawing poly(vinyl alcohol) from solution-grown crystal mats , 1990 .

[15]  K. Yamaura,et al.  Preparation of high modulus poly(vinyl alcohol) by drawing , 1990 .

[16]  Y. K. Levine,et al.  On the distribution of dye molecules in stretched poly(vinyl alcohol) , 1988 .

[17]  A. Hayakawa,et al.  Properties of syndiotactic‐rich poly(vinyl alcohol) thin films in water. VI. Elastic behavior of undrawn/annealed thin films by repeated elongation/contraction in water , 1988 .

[18]  T. Kunugi,et al.  Mechanical properties and superstructure of high-modulus and high-strength nylon-6 fibre prepared by the zone-annealing method , 1982 .

[19]  Y. Ikada,et al.  Surface Modifications of Cellulose and Polyvinyl Alcohol, and Determination of the Surface Density of the Hydroxyl Group , 1980 .

[20]  Jacqueline I. Kroschwitz,et al.  Encyclopedia of Polymer Science and Technology , 1970 .