Synergistic toughening and reinforcement of PLA by PPCU and bamboo charcoal

Polylactic acid (PLA), owing to its high strength, excellent processability, abundant renewable feedstocks, and biodegradability, has emerged as a highly promising candidate in the field of bio-based polymer materials. However, its inherent brittleness significantly limits its applicability in broader engineering scenarios. To address this limitation, this study employed twin-screw melt blending to incorporate polypropylene carbonate-thermoplastic polyurethane (PPCU) and bamboo charcoal (BC) into the PLA matrix and successfully prepared a series of PLA/PPCU/BC composites. The synergistic effect of PPCU and BC markedly enhanced the tensile strength and toughness of PLA. Noticeably, the tensile strength and elongation at break of PLA/PPCU/3BC was increased from 42.9 MPa and 3.2% of neat PLA to 45.2 MPa and 30.2%, respectively. Meanwhile, the impact strength increased markedly from 1.5 kJ/m² to 4.4 kJ/m². Differential scanning calorimetry (DSC) analysis further demonstrated that BC acted as an effective heterogeneous nucleating agent within the PLA matrix, significantly increasing the crystallinity and accelerating the crystallization process of the composites. In addition, PLA/PPCU/BC composites showed improved storage modulus, loss modulus, and complex viscosity. Overall, this study presents a green and efficient blending strategy to develop PLA-based composites with high strength, high toughness, and benign processability, providing new insights into the high-performance development and sustainable modification of PLA.