Advancing Mechanical Properties of Polypropylene Matrix Composites: Analysis of Diverse Reinforcing Fillers

Currently, much research is being conducted on increasing the strength of thermoplastic polymers using various additives. Polypropylene (PP) is widely used in the automotive industry and electrical equipment. In this paper, using various reinforcing particles/fibers, including calcium carbonate, CaCO3, (at 20%, 25%, and 30% weight percentages), 20% talc, and 20% barite particles, as well as 30% glass fibers (GFs) (with varying L/D ratios, 200, 250, and 300) were integrated. First, PP and additives were mixed homogeneously by an extrusion process, and then test samples were made by high-pressure injection of the extruded product into the mold. Various tests, including tensile, impact, and melt flow index (MFI) tests, were conducted to investigate the effect of additives on the properties of composites produced by plastic injection molding. SEM analysis was used to examine the fracture cross-section of the samples and the distribution of additives. Results revealed significant outcomes across multiple tests: the addition of reinforcing particles led to a reduction in yield strain while creating notable variations in yield strength. Charpy impact tests demonstrated varied energy absorption, with the highest observed in the 30% GF sample (with L/D ratio of 350). Furthermore, the incorporation of reinforcing particles and fibers increased the heat deflection temperature, with the 30% GF sample exhibiting the highest value. Additionally, reinforcements effectively mitigated shrinkage, with significant reductions noted in samples containing talc and GF. The PP sample displayed a shrinkage rate of 19.1%. This figure significantly decreased to 1.42% and 0.26% for the samples reinforced by talc and GF [L/D = 350]. Furthermore, the introduction of GFs resulted in a decreased MFI, while other particles exhibited minimal impact.