Waxy polyethylenes from solution thermolysis of high density polyethylene: inert and H-donor solvent dilution effect

High density polyethylene batch thermolysis has been performed in dilute solutions to obtain waxy products with number-average molar masses in the range of 2000 to 6000 g mol(-1). In relation to a classical bulk thermolysis (390 degrees C, 6 h) which affords branched waxy polymers, dilution with phenylether permits controlled diffusion reactions modifying the product characteristics: low molar masses, narrow distribution, high crystallinity, rich in alpha-olefins and few long branching formation. A hydrogen donor solvent (tetralin), acting on the free radical degradation pathway, affords a lower fragmentation level of the main chains and short chains branching. In addition, a high level of tetralyl radicals grafting on the alpha-olefin is observed. Adjustment of the process conditions might give tailor-made waxy polymers to use just as they are or after chemical modifications of the olefinic functions. (C) 1999 Elsevier Science Ltd. All rights reserved.