Birefringence and dichroism of oriented epoxy thermoset films

A series of oriented liquid-crystalline epoxy thin films were prepared by t he in situ polymerization of a liquid-crystalline diepoxide, 1,4-phenylene bis[4-(2,3-epoxypropoxy)benzoate], with an aromatic diamine, 4,4'-diaminobi phenyl, in a 7.0-T magnetic field. The birefringent measurements of the ori ented films were made from 543.5 to 830 nm. In this range, the values of bi refringence (Deltan) range from 0.155 to 0.130. When they are extrapolated to the microwave region, Deltan = 0.105. The dichroism of a guest azo dye, 4-(4-nitrophenylazo)-3-hexyloxyaniline, in the oriented thin films was exam ined in the visible region. From the results, the order parameter of the po lymer was calculated to 0.65 by extrapolating the concentration of the gues t azo dye to zero. The guest azo dye compound does not affect the birefring ence. (C) 2001 John Wiley & Sons, Inc.