We investigated the enhancement of interfacial compatibility between polylactide (PLA) and high-density polyethylene (HDPE) for 3D-printing filament production to address the growing plastic waste crisis. Although HDPE is readily available and exhibits favorable mechanical properties, several studies have reported poor miscibility between traditional polyolefins and PLA. This incompatibility often results in phase separation, warping, and reduced mechanical performance in fused deposition modeling (FDM) applications.
We explored two primary mechanisms to improve compatibility: the incorporation of lignin as a biomaterial additive and surface modification of HDPE via ultraviolet (UV) irradiation. We utilized a desktop extrusion system to produce filaments and employed comprehensive material characterization techniques, including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing to evaluate the blends.
Our results indicated that low-HDPE-content filament blends, when fortified with UV treatment or additives, exhibited improved interlayer adhesion and structural stability compared to untreated controls. Overall, our work contributed to the advancement of sustainable additive manufacturing by demonstrating a feasible method for upcycling HDPE waste into functional 3D-printing filaments and engineering materials.