Development of PLA/recycled-desized carbon fiber composites for 3D printing: Thermal, mechanical, and morphological analyses

This study investigated the incorporation of desized short recycled carbon fiber (rCF) into polylactic acid (PLA) matrix for fused deposition modeling (FDM) printing. Composite filaments were produced by ball milling mixing and then melt extrusion, unlike the majority of the existing studies, which employed multi-cycle compounding/extrusion. Composite filaments with different loadings of rCF were produced. Tensile testing was carried out to evaluate the influence of rCF on mechanical properties. The morphology of the extruded filaments, as-printed, and fractured samples was assessed through scanning electron microscopy (SEM). The thermal properties of the produced filaments were also evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The SEM images demonstrated a homogeneous distribution of the rCF within the PLA matrix, with good adhesion between PLA and desized rCF. DSC showed lesser thermal alteration in the pure PLA filaments compared to PLA pellets due to the currently used mixing methodology. TGA results showed enhanced thermal stability with adding rCF into PLA. Incorporation of rCF increased tensile modulus up to 58.30 % compared to pure PLA. The tensile modulus of the PLA/15 %rCF composite was higher than that of the commercially available PLA/15 %vCF composite (19.64 % enhancement) while showing similar strength. In fractured specimens, the intra-layer failure mechanism was dominated, while no significant interlayer separation was observed. The study demonstrates the potential of employing eco-friendly desized rCF as a substitute for vCF in producing fiber-reinforced PLA for FDM printing.