Composites Based on Polypropylene Modified with Natural Fillers to Increase Stiffness

Composites based on a polypropylene matrix with coffee ground powder, wood flour and tuff of a mass weight of 12.5wt% were produced by the method of injection moulding. Tests of tensile and bending strength properties were carried out and Charpy impact was determined at three temperatures: -24°C, 22°C and 80°C. Scanning electron microscopy (SEM) images were taken to assess the effects of reinforcement and homogenization of mixtures and to determine the characteristics of the microstructure. Composites with 12.5wt% coffee ground powder, wood flour and tuff were characterized by an increase the elastic modulus. Tensile strength slightly decreased for composites with ground coffee grains and tuff.