Pn. Lavrenko et Ov. Okatova, HYDROLYTIC THERMAL-DEGRADATION OF POLY(NAPHTHOYLENEIMIDE BENZIMIDAZOLE) IN CONCENTRATED SULFURIC-ACID, Journal of applied polymer science, 56(1), 1995, pp. 97-102
Translational diffusion in 96% H2SO4 and intrinsic viscosity of poly(n
aphthoyleneimide benzimidazole) (PNIB) have been investigated in diffe
rent stages of its degradation in solution in the temperature range fr
om 65 to 120 degrees C. The degradation rate constant k has been deter
mined from the change in molecular weight M of degraded products with
time at the fixed temperature of solution. The activation energy of th
e process E was calculated from the temperature dependence of k. The d
ifference in E values at low and high temperatures was found. At degra
dation temperatures above 90 degrees C, the activation energy of hydro
lysis was obtained as E = 133 kJ/mol, which coincides with that of aro
matic polyamides in sulfuric acid. The data obtained are compared with
the results of the investigations of optical properties of products o
f PNIB degradation in solution and PNIB stability in the solid state.
An explanation of anomalies observed during PNIB degradation at low te
mperatures is suggested. (C) 1995 John Wiley and Sons, Inc.