This study investigates the effect of talc particle size on the structure–property relationships and physicomechanical performance of polypropylene block copolymer (PP-BC) composites. Particular attention is given to the role of talc as a mineral filler in modifying intermolecular interactions within the polymer matrix and interfacial adhesion between the filler and matrix phases. Composite samples containing talc with different particle size distributions were prepared and evaluated in terms of elastic modulus, yield strength, hardness, Izod impact strength, heat deflection temperature (HDT), and melt flow index (MFI). The results demonstrate that decreasing talc particle size leads to a significant improvement in stiffness and thermal resistance due to enhanced dispersion and increased interfacial surface area. Fine talc particles promote stronger filler–matrix interactions, resulting in improved load transfer efficiency and restriction of polymer chain mobility. As a consequence, the elastic modulus and HDT increase, while the melt flow index decreases, indicating higher melt viscosity. However, excessive reduction in particle size may adversely affect impact strength due to stress concentration effects. Overall, the study confirms that optimizing talc particle size is a key factor in tailoring the balance between stiffness, strength, and toughness in polypropylene-based composites. The findings provide practical guidance for the development of high-performance polymer composites for industrial applications.

Polypropylene, elastic modulus, Izod impact strength

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