THERMOGRAVIMETRIC CHARACTERIZATION OF POLY(METHYL METHACRYLATE) PHOTOPOLYMERISED BY COLLOIDAL CADMIUM-SULFIDE

The thermal stability of poly(methyl methacrylate) (PMMA) photopolymer ised using colloidal cadmium sulphide as the photoinitiator was studie d by thermogravimetry (TG) and differential TG (DTG). The thermal stab ility of the CdS initiated PMMA was greater than that of conventional radically polymerised PMMA and approached that of anionically prepared PMMA. The DTG curve of the CdS initiated PMMA was a composite of four peaks, three of which correspond to the three peaks observed in the D TG curve of standard radically prepared PMMB. It is suggested that the additional peak arises from a new mode of depolymerisation initiation , that is, from chain end unsaturation introduced into the polymer cha in during polymerisation initiation with the colloidal CdS.