THE THERMAL-DEGRADATION OF POLY(PROPYLENE OXIDE) AND ITS COMPLEXES WITH LIBR AND LII

The thermal degradation of poly(propylene oxide) (PPO) in an inert atmosphere proceeds by random homolytic scission of C-O and C-C backbone bonds to yield short chain fragments, and several volatile and gaseous products. The latter, which arise from reactions of the chain-end radicals formed by random scission, comprise mainly CH3CHO, CH3CH2CHO, CH3COCH3 and CH3CH = CH2. Complexation with LiBr and LiI leads to a marked increase and decrease in thermal stability, respectively. The changes in the nature and quantities of the products of degradation can be explained, in general, by the interaction of the Li+ ion with the oxygen atoms in the backbone and with the oxygen-centred radicals formed by homolytic scission. The anions also participate in the decomposition processes by reactions which are, as yet, obscure.