Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE PLA/ground tea leaf (GTL) composite filaments were developed using a masterbatch-assisted melt extrusion process for sustainable FDM applications. GTL acted as a bio-waste filler that slightly increased hardness and crystallinity while reducing tensile and impact properties at higher loadings. The composite filaments maintained stable melt flow and smooth 3D printability, demonstrating their potential as cost-effective and eco-friendly printing materials.

ABSTRACT
This study aimed to develop composite filaments from polylactic acid (PLA) and ground tea leaves (GTL), a waste material derived from tea consumption. PLA/GTL composite filaments were fabricated via melt extrusion using a 90:10 PLA/GTL masterbatch incorporated into PLA at loadings of 0–40 phr. The mechanical, thermal, and printability properties of the filaments were evaluated. The results showed that tensile strength, elongation at break, and impact strength decreased by approximately 7.12%–16.69%, 12.71%–21.35%, and 7.40%–33.30%, respectively, with increasing GTL content, whereas hardness slightly increased by 1.26%–2.78%. Notably, the flexural strength and modulus improved by up to 11.79% and 8.77%, respectively, at 10 phr GTL loading. The melting temperature remained essentially unchanged, while the glass transition and crystallization temperatures were lower than those observed for neat PLA. The composite filaments exhibited stable 3D printability with smooth surfaces and no die jamming, demonstrating their potential as cost-effective and sustainable 3D printing materials that valorize tea leaf waste. Furthermore, statistical analysis using one-way ANOVA confirmed that the differences in the mean mechanical properties were statistically significant.