Aging studies of a polypropylene and natural rubber blend

The literature relatively lacks results and data related to the direct influence of physical aging on the properties of polypropylene and natural rubber blend; so, the objective of this research was to study the influence of thermal and ultraviolet (UV) aging on a natural rubber (NR) SMR-ω and polypropylene (PP) blend. This toughened blend is generally used for the fabrication of automobile parts and in the construction industry. The loading of the NR was 10, 20, 30, 40 and 50 wt%. The blends were prepared by calendering followed by melt extrusion and it was subjected to XRD (WAXS) analysis, mechanical testing, thermal and UV aging, and optical microscopy (OM) observations. The results obtained by X-ray characterisation show that the adding of this kind of rubber does not affect the crystalline structure of the polypropylene matrix. Moreover, the adding of the rubber shows a decrease of the obtained material tensile strength and a valuable increase of the elongation at break. The shore A hardness decreases slightly as the percentage of the natural rubber increases. The optical microscopy indicates the apparition of cracks at the sample surfaces and debonded rubber domains from polypropylene matrix induced by UV and thermal aging.