Mechanical and environmental evaluation of ground calcium carbonate (CaCO<inf>3</inf>) filled polypropylene composites as a sustainable alternative to virgin polypropylene

Abstract

Polypropylene (PP) has raised environmental concerns particularly for its depletion of fossil-fuels and contribution to climate change. To lower environmental impacts, PP can be combined with biobased fillers such as calcium carbonate (CaCO3). The mechanical and environmental properties of CaCO3 filled PP have not yet been explored in depth. Therefore, this study examines the aesthetic, tensile, flexural, impact, and environmental (via life cycle assessment) properties of injection moulded CaCO3 filled PP with filler content ranging from 0% to 40% at 5% increments. As filler percentage increased, yield strength decreased (0% CaCO3: 17.68 MPa, 40% CaCO3: 12.73 MPa), but young's modulus, flexural modulus, and impact strength increased (respectively 69%, 51%, and 35% greater than pure PP). Flexural strength increased initially at 5% CaCO3 but then declined as more filler was added. A yellowish hue was observed within all blends which growed stronger with more filler. The addition of CaCO3 reduced the environmental impact for all 11 impact categories. For every 5% of CaCO3 added, the material's global warming potential (GWP) decreased by 100g CO2 eq. per functional unit (1000 cm3) of composite. Abiotic depletion of fossil fuels declined by 32% when 40% CaCO3 was added. In addition to this study, it would be beneficial to explore other factors that affect the properties of CaCO3 filled PP such as particle size, particle distribution, and binding additives.