Effect of Recycling and UV Ageing on the Properties of PLA-Based Materials Used in Additive Manufacturing.

This article focuses on the possibility of using biodegradable polymer-composite materials in additive manufacturing via fused deposition modelling (FDM) 3D printing. The main objective was to experimentally verify the technical feasibility of the repeated use of recycled PLA and PLA composites containing 10% natural coffee-ground (CG) filler in a print-degradation-recycling-print cycle. Special attention was paid to simulated ultraviolet radiation as a degradation factor affecting the materials' mechanical properties. Pure PLA and PLA_CG were compared at four levels of degradation time and after subsequent recycling. The results show that the inclusion of coffee-ground filler slightly reduces the initial strength but enhances the 3D-printed material's resistance to UV degradation and thus extends its functional service life. Unlike pure PLA, which loses its processability after 12 weeks, PLA_CG retains structural integrity and mechanical functionality. The research confirms the potential of recycled PLA composites with natural fillers for sustainable manufacturing and supports their use within a circular economy framework.