synopsisIn a previous paper it was shown that the vulcanization obtained with ethylene-propylene-diene terpolymer is equivalent or superior to that obtained with ethylenepropylene copolymer when a peroxide-dimethacrylate coagent cure system was used. In order to determine the effect of the unsaturation on the physical properties in the terpolymer, the terpolymer had been hydrogenated to remove the double bonds. Infrared spectra and bromination were used to check the extent of hydrogenation. Tensile strength, Shore A hardness, per cent elongation, and modulus indicated no decrease in vulcanization efficiency after hydrogenation. The data show that the unsaturation in the terpolymer does not contribute to the vulcanization cure with the peroxide-dimethacrylate coagent curing system.

This study was conducted to investigate the possibility of one‐stage molding process skipping compounding extrusion for the fabrication of cross‐linked polyethylene (PE)‐ground tire rubber (GTR) composites. The process resulted in a wide range of composites with various properties. Response surface methodology technique based on central composite design was employed with variables: polyethylene content (PE: % per polymer fraction), dicumyl peroxide (DC: % per polymer fraction), molding residence time (RT: min), and filler content (F: % per total mass). A quadratic model was able to significantly describe tensile strength, elongation at break (EB), and impact resistance/energy of the composites as a function of PE, DC, RT, and F. Tensile strength (TS) was positively affected by PE, DC, and RT; however, it was negatively affected by the filler content. Tensile EB and impact resistance of the composites were improved by DC and RT, while reduced by PE and filler increment. Composites with TS, ultimate elongation, and impact resistance of 11.5 MPa, 140%, 244 MJ/m2, respectively, were obtained under optimized conditions. The nonextrusion molding process is recommended for the fabrication of PE‐GTR composites due to the higher stiffness/tensile modulus and a slightly lower strength of nonextruded composites compared to the extruded composites.