THE SYNTHESIS AND EVALUATION OF NOVEL PHOTOSENSITIZERS FOR CONTROLLEDDEGRADATION OF POLYETHYLENE

Six novel additives have been synthesised by substitution of benzophen one in the 4-position with 2-hydroxybenzophenone or 4-amino-2,2,6,6-te tramethyl piperidine groups. The spacing between the chromophores was varied by alkyl groups of n = 4, 6 and 8 CH2 units. The additives were incorporated into polyethylene and the rates of thermal and photo-oxi dation monitored using FTIR spectroscopy. The data show a number of in teresting features that appear to be dependent not only on the nature of the stabiliser moiety but also the value of n. Their behaviour is c ompared with mixed compositions based on benzophenone with 2-hydroxy-4 -octoxybenzophenone and 2,2,6,6-tetramethyl-4-piperidinyl sebacate. Th e possibility of these compounds for the control of thermal and photo- oxidation of polyolefins is discussed. (C) 1996 Elsevier Science Limit ed