DYNAMIC BIREFRINGENCE IN SOLUTIONS OF POL YNAPHTHOILENEIMIDOBENZIMIDAZOLE DURING HYDROLYTIC THERMAL-DEGRADATION

Dynamic birefringence in solutions of polynaphthoileneimodobenzimidazo le subjected to hydrolytic thermal degradation in 96% sulfuric acid wa s studied. The polymer in solution was preliminarily heated at differe nt temperatures between 65 and 120-degrees-C. It was then examined at 23-degrees-C using dynamic birefringence and viscometry. The intrinsic viscosity of solutions and molecular mass of the fragments resulting from degradation were both found to decrease with an increase in the t reatment temperature. At the same time, the shear-optical coefficient first increased and, then, at treatment temperatures exceeding 90-degr ees-C, decreased in parallel with a decrease in intrinsic viscosity. V arious causes of the discovered anomaly are discussed.