CHEMILUMINESCENCE FROM OXIDATION OF POLYPROPYLENE - CORRELATION WITH PEROXIDE CONCENTRATION

The chemiluminescence (CL) on heating in an inert atmosphere has been measured for samples taken at various times during oxidation of polypr opylene (PP). Proportional relationships were obtained when the integr ated emission (TLI) was plotted against peroxide concentration for all studied sets of parameters. Changes in melting temperature and molecu lar weight with ageing time were found to correlate with changes in th e TLI. Oxidised PP was exposed to dimethylsulfide (DMS) for different periods with subsequent measurements of the CL and the peroxide concen tration. The peroxide concentration has earlier been found to exhibit a two-step decay with DMS exposure time, indicating two fractions of p eroxides with different reactivity. The CL was found to follow the sam e two-step decay, indicating that both peroxide fractions contribute t o CL. The oxidative stability of PP, measured by CL induction times in oxygen, increases when the polymer is exposed to DMS. (C) 1996 Elsevi er Science Limited