Interfacial interaction in polypropylene-natural rubber blends: role of natural rubber on morphological, rheological, and mechanical evolution

Role of natural rubber (NR) on modifying the interface, morphology and mechanical properties of polypropylene (PP)-NR blend system, is investigated. PP-NR blends with different loading of NR (0, 10, 20, 30, 40, and 50 wt/wt %) were prepared via melt mixing technique. NR, depending on its loading, actuates dramatic phase morphology transformation; from well-discrete matrix droplet to a co-continuous type morphology. This in turn lowers the relaxation of dispersed NR phase as evident by rheological studies. Similarly, the coarsening of morphology from discrete droplet-matrix structure produces synergistic improvement in mechanical properties especially the impact strength. Besides, contact angle studies were carried out to determine the various wettability parameters and the interfacial energy is theoretically calculated using geometric-mean equation.