A theoretical framework is presented to describe the optical properties of polarizers produced by tensile deformation of semicrystalline polymers containing dichroic dyes. In the model it is assumed that orientation of both the host polymer and guest molecule occurs in the f f i e mode. The development of optical anisotropy with Orientation is described using an aggregate model. The theory is employed to evaluate the optical Characteristics of the polarizers, i.e., dichroic ratio, order parameter, polarizing efficiency, and single-piece transmittance. Good agreement is observed between theoretical predictions and experimental data produced in this work on oriented linear polyethylendSudan Red polarizing films. It is shown that the model is useful to estimate the limiting polarizing efficiency and single-piece transmittance of the polarizing films at hand.
IntroductionSeveral processes exist for the production of polymeric sheet polarizers, chiefly for use in the visible wavelength range.i-9 These polarizers are widely employed in, for instance, liquid-crystalline display applications. In most of the aforementioned processes, semicrystalline polymers, such as poly(viny1 alcohol) and polyolefins, are oriented by tensile drawing at temperatures close to, but below, the melting temperature of the p~l y m e r ; l -~ dichroic chromophores are introduced in the oriented films either by chemical modification of the polymer or by incorporation of dichroic dyes in the films prior to or