STUDIES ON THERMAL-DECOMPOSITION KINETICS OF POLYVINYL NITRATE

Non-isothermal TG curves for four samples of polyvinyl nitrate (PVN), having 15.71%, 14.95%, 13.34% and 11.76% nitrogen contents, were obtained at 5-degrees-C/min heating rate. The weight loss of PVN samples depends directly on their % N and occurs in three or more temperature zones. For PVN with 15.71% N (max 15.73% N in theory), the main decomposition step results in more rapid and complete weight loss than for PVN with lower % N, probably due to higher oxygen balance of the former. The TG data were subjected to kinetic analysis using a computer programme. For each decomposition step, the kinetic parameters (E and A) and the regression coefficient (r) were calculated on the basis of several kinetic models and equations consistent with the Arrhenius relationship. It was concluded that the thermal decomposition kinetics of all four PVN samples are best expressed by the Random nucleation model (Mampel unimolecular law) first-order reaction. For the initial and slowest decomposition step, E ranged between 188 kJ/mol - 217 kJ/mol and ln A between 46.88 s-1 - 60.13 s-1. The ln A versus E plots for all PVN samples exhibited a linear relationship, probably due to the kinetic compensation effect.