THERMAL-DECOMPOSITION OF ANIONIC AND EMULSION POLYMERIZED POLYSTYRENES

The thermogravimetric behavior of anionic and emulsion polymerized polystyrenes was investigated in nitrogen at a heating rate of 18°C/min. Kinetic data were obtained by least squares analyses of experimental points obtained by differentiating primary thermograms. Degradation was generally zero order for about the first 25% of the reaction and first order thereafter. No molecular weight effects were observed for anionic polystyrenes with M ≥ 1 × 105. Anionic and emulsion polystyrenes differed significantly in thermal stability. Degradation of emulsion polymers proceeded more slowly and with higher activation energies in both the zero‐ and first‐order regions. Activation energies for anionic polystyrenes were 28 and 44 kcal/mole in the zero‐ and first‐order domains while the corresponding values for emulsion polymers were 36 and 60.5 kcal/mole, respectively. No tacticity differences were detected in 220 MHz NMR spectra. The differences in thermal stability are attributed to differences in end groups in the two polymer types. Copyright © 1979 John Wiley & Sons, Inc.