Effect of Polypropylene‐Grafted‐Maleic Anhydride and Rice Husk Particle Size on <scp>3D</scp> ‐Printing Filament Composites From Recycled Polypropylene

ABSTRACT This study evaluates the combined roles of particle size and the addition of maleic anhydride polypropylene (PP‐g‐MAH) to improve 3D printing and mechanical properties of composite filaments based on recycled polypropylene (rPP) and rice husk (RH) obtained as a by‐product of rice production. Particle size and PP‐g‐MAH content are shown to be critical in shaping the filaments' characteristics. Particle size below 250 microns and 5 wt.% of PP‐g‐MAH resulted in smoother surface finish, improved adhesion between RH particles and the rPP matrix, reduced crystallinity, and enhanced flow properties. Moreover, the study highlighted a significant reduction in the warping effect when RH and PP‐g‐MAH were incorporated, making the composite filaments more suitable for 3D printing applications. Besides, adding PP‐g‐MAH improved the printed parts' tensile and flexural properties, promising stronger and more sustainable 3D‐printed products. This research contributes to developing eco‐friendly 3D printing composite materials aligned with Circular Economy principles.