Hollow microspheres - poly-(propylene) blends: Relationship between microspheres degradation and composite properties

In recent decades, the weight of passenger vehicles has constantly increased. This led to a rise in fuel consumption and to higher CO2 emissions. On this basis, and in order to meet the European regulatory requirements on CO2 emissions (less than 95 g CO2/km) by 2020, vehicle weight reduction is currently a privileged research axis. In this study, hollow microspheres (HM), used as lighter fillers, were incorporated to a high impact polypropylene (HIPP), a copolymer commonly used for car bumpers. We explored the impact of pilot-scale melt-processing on these HM and assessed the influence of their addition on the copolymer density and on its properties. We showed that two commercially available HM can better withstand the melt-processing and allow a significant reduction of the polymer density. Good agreement was found between experimental data of tensile strength and the Nicholais-Narkis model prediction on this parameter.