Synthesis of branched polyethylene by catalytic degradation-isomerization of high-density polyethylene in the presence of silica-alumina catalyst

Branched polymers were synthesized through the process of molecular-weight-decrease reaction in the presence of silica-alumina catalyst. Gaseous products, liquid products, branched oligomers (Mw=400) and branched polymers (Mη=1.1x104-2.8x104) were obtained by the reaction. The straight-c1iain branches (C1-05, C6 and/or higher) and branched branches (2-ethylhexyl, 2-ethylpemtyl and 2-ethylbutyl) were found in the branched polymer by means of 13C-NMR measurements. The highest concentration of total branches in the polymer was 71 branches/1000 CH2 and the yield of the polymer was 20 wt%. This concentration is much higher than that in commercial polyethylenes containing 10-20branches/1000 CH2. Similar branches were, also found in the branched oligomer.