The effect of quartz and rubber seed oil loading on curing, tensile and morphological properties of natural rubber and ethylene propylene diene monomer rubber (NR-EPDM) blending

The necessity of renewable filler and plasticizer has become a big concern to substitute petroleum based that has some negative impacts. Quartz is potentially could be used as a reinforcing filler to improve its physical mechanical properties. While, rubber seed oil also could be applied as plasticizer. This research studied the effect of rubber seed oil (RSO) loading as natural plasticizer on its blending compatibility between NR-EPDM and Quartz. The effect of plasticizing compatibility was examined by applying 1; 1.5 and 2 phr of RSO in NR-EPDM blending with different loading of Quartz (30; 40; 50; and 60 phr). The curing characteristic, tensile properties, morphological/ micro-structure (SEM) and the thermal ageing of those composites were evaluated. The results shows that loading of quartz has significant effect on the decreasing cure rate index and increasing the scorch time. Similarly, loading quartz cause decreasing the value of maximum and minimum torque slightly as well as the cross linking density of the composites. Moreover, RSO cause cure rate index decreases which means RSO is able enough to use as plasticizer. The SEM-EDX confirmed that results. The loading of quartz in NR-EPDM composites improve significantly the tensile strength, elongation at break and also hardness value. However, the thermal ageing (circulate hot air at 70 °C for about 48 hours) cause slightly effect to the deterioration of the vulcanizates as showed by the decreasing value of hardness about 1-5 Shore A, the decreasing of tensile strength about 3-6 N/m2, the decreasing of elongation at break 50 - 110 %. This is due to serious cross linking effect, stiffening effect and thermal oxidation in the composites as explained in this paper.