Fly ash incorporation in polypropylene/ethylene-vinyl-acetate (PP/EVA) blends: An in-depth morphological and performance study

This study examines the properties of fly ash (FA)-reinforced polypropylene/ethylene-vinyl-acetate (PP/EVA) blend composites, focusing on morphological, thermal, mechanical, and rheological behavior of binary (PP/FA) and ternary (PP/EVA/FA) composites. Three composite series were produced: single PP matrix, 80/20 wt.% PP/EVA blend (B 80/20 ), and 60/40 wt.% PP/EVA blend (B 60/40 ), each with 0–20 wt.% FA loadings. Binary composites increase stiffness by 25% but reduce ductility. In B 80/20 blend, a sea-island morphology forms, producing ternary composites with a core-shell microstructure, in which FA particles are encapsulated by EVA copolymer, providing 26% ductility increase. At 40 wt.% EVA, a co-continuous structure emerges, resulting in composites that combine core-shell and separate microstructure, enhancing ductility by 83%. FA also improves melt elasticity and viscosity, promoting processing stability and product quality. Overall, this work highlights the importance of microstructure in determining composite performance, enabling the development of materials with customizable balances of stiffness and ductility for diverse applications.