The Kerr effect in predeformed glassy polymers

The Kerr effect in nondeformed (isotropic) and predeformed polymer networks is theoretically studied within the framework of a model of three-chain ne twork with Freely jointed chains between junctions. Also considered is the Kerr effect for macromolecules with a zero constant dipole moment. where th e optically anisotropic chain segments are oriented in the external electri c field due to the field-induced dipole moments. Dependence of the average difference [Delta a] = [a(parallel to) - a(perpendicular to)] of the chain segment polarizabilities in two principal directions (a(parallel to) and a( perpendicular to) along and across the field. respectively) on the field st rength is calculated. The birefringence parameters of predeformed polymer n etworks exposed to strong electric fields can be used to evaluate the densi ty of cross-links. The electrooptical parameters of the polymer films are c ompared to those of polymer solutions (melts). provided that the chain segm ents in both systems have identical chemical structures and equal molecular weights.