Mechanical and environmental evaluation of ground calcium carbonate (CaCO3) 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.