Abstract: Molecular structure of waste rubber powder was modified via desulfurization, free radical polymerization, curing cross-linking, and grafting reaction in order to improve the compatibility with high density polyethylene (PE-HD). The effect of the modification of waste rubber powder on the blends was investigated. When untreated waste rubber powder was used, the tensile strength and elongation at break of the blends decreased with increasing rubber loading. However, with adding 60 % of treated waste rubber powder, 2 % of PTC-R, 1.2 % of DCP, 1 % of sulfur, and 1 % of promoting agent, the tensile strength and elongation at break of the blends reached 25 MPa and 250 %, increased by 350 % and 201 %, respectively, compared with those based on untreated waste rubber powder. Sulfur was effectively stripped down by catalytic regeneration of rubber reducer PTC-R. The tensile strength and elongation at break were developed significantly because of synergistic effect between DCP and sulfur.

Key words: waste rubber powder, devulcanization, dynamic vulcanization, cross-linking, high density polyethylene