HYDRODYNAMIC PROPERTIES OF POLY(P-PHENYLE NE OXADIAZOLE) IN VARIOUS STAGES OF HYDROLYTIC THERMAL-DEGRADATION IN SULFURIC-ACID

Translational diffusion of poly(1,4-phenylene-1,3,4-oxadiazole) in 96% H2SO4 was studied and the intrinsic viscosity of the polymer solution was measured in various stages of degradation at temperatures from 82 to 105 degrees C. The rate constant of the degradation process was de termined from variation of the molecular mass of the degradation produ cts with time at a fixed solution temperature, and the activation ener gy of the process was calculated using the temperature dependence of t he rate constant. The activation energy (E = 103 +/- 7 kJ/mol) is lowe r than that for the hydrolysis of aromatic polyamides in sulfuric acid . According to the hydrodynamic data, the degree of coiling of the deg radation products is the same as that of the intact (non-degraded) mac romolecules. This indicates that elements of the chemical structure re sponsible for the short-range interactions in the macromolecular chain are retained in the course of degradation.