The influence of maleic anhydride-grafted polymers as compatibilizer on the properties of polypropylene and cyclic natural rubber blends

The enhancement of mechanical properties of immiscible blend, i.e. polypropylene/ cyclic natural rubber (PP/CNR), could be achieved by incorporating a compatibilizer into the blend system. The main challenge is how to compatibilize the two materials with distinct characteristic of saturated and apolar structures. As compatibilizers, copolymer of maleic anhydride-grafted polypropylene (POLYBOND 3002 and POLYBOND 3200) and maleic anhydride-grafted cyclic natural rubber (CNR-g-MA) were incorporated with PP/CNR (80/20 wt.%) blends in different weight ratios. The impact of those compatibilizers were analysed using Scanning Electron Microscope (SEM), which shows a homogenous phase of PP matrix indicating a homogenous dispersion of CNR into PP matrix. Thermogravimetry (TGA) analysis confirmed that the addition of compatibilizers improved the thermal stability of blends. The Differential Scanning Calorimetry (DSC) curve shows that the glass transition temperature (Tg) was significantly decreased due to the maleic anhydride-grafted polymers incorporation. The decrease of CNR’s Tg value implies that the incorporation of maleic anhydride-grafted polymer into PP/CNR blends can improve blend compatibility. The compatibilization was further confirmed by an increase in tensile strength of compatibilized blends.