Preparation And Application Of Polyvinyl Alcohol Dispersed Liquid Crystal Films

Polarizer is a kind of optical element which can be used in almost all kinds of optical fields. The earliest artificial polarizer is a kind of absorbing polarizer which has many advantages such as easy preparation and wide application. However, it is easy to depolarize and has a low light utilization. Those disadvantages cannot be ignored. Therefore, two kinds of novel polarizing films, reflecting polarizer and scattering polarizer, have gradually gained more popularity. The scattering polarizer is a kind of optical function film. The polarizing film is opaque and has a certain degree of fog. The method to prepare this scattering polarizer is as follows:preparing the polymer dispersed liquid crystal casting film, linear stretching the film to make the liquid crystal molecules oriented. When the nature light incident on the film, the light which is parallel to the stretching direction is scattered, and the light which is perpendicular to the stretching direction is transmitted.In this paper, PVA dispersed liquid crystal films were prepared by sol-casting method, and their application on the novel transparent projection screen were discussed. The detailed content of the investigation is divided into the following two partsFirstly, the effect of additives on the properties of PVA dispersed liquid crystal films was discussed. When preparing polyvinyl alcohol dispersed liquid crystal sol, adding glycerin in order can improve the physical properties and mechanical properties of casting film. The results showed that the mechanical properties of PVA dispersed liquid crystal films were excellent when the concentration of polyvinyl alcohol was 15%, the concentration of glycerin was 15 phr. Compared with the PVA dispersed liquid crystal films prepared without adding glycerin, the tearing strength was increased by 96%, the tensile strength was increased by 123.37%, and the tensile elongation was increased by 360.02%. The polarizing properties of PVA dispersed liquid crystal films were favorable when the concentration of polyvinyl alcohol was 15%, the concentration of liquid crystal in the sol was 12%.Secondly, the effect of processing technology of PVA dispersed liquid crystal films on the film properties was discussed. The apparent performance and mechanical properties were good when casting temperature was setting 50-60?, casting roller speed was setting 2.6-3.0 m/min. Linear stretch the PVA dispersed liquid crystal casting film in 80? using the self-made tensile machine. The polarizing performance of the film is excellent when the draw ratio was 4 times. The degree of polarization reached 82.46%. The product can be applied to the transparent projection screen. The new technology products are looking forward by the market.