Effect of maleimide curing on mechanical properties of ground tyre rubber/waste polypropylene blends

Blends of ground tyre rubber and waste polypropylene with a maleimide curing system (50: 50blends of ground tyre rubber/waste polypropylene) were prepared in a Haake Rheocord Polylab System, at 180°C and 90 rev min-1 for 5 min. The curing agent and the activator used were N,N'- meta-phenylene dimaleimide (HVA-2) and di(tert-butylperoxyisopropyl) benzene (DTBPIB) respectively. The HVA-2 level varied from a to 5 parts per hundred parts (pphp), while the DTBPIB level varied from a to 1 pphp. Melt viscosity, tensile strength and elongation at break showed an increase with HVA-2 content, while the impact energy showed an optimum at 3 pphp level. The addition of the DTBPIB increased melt viscosity further and produced a homogeneous phase morphology of the blends. Impact energy improved with the DTBPIB level, while elongation at break and tensile strength showed an optimum at 0·6 pphp. Swelling behaviour and gel/sol from the boiled xylene extractions were studied, and the results obtained were correlated with the impact and tensile properties