Consolidation behavior of HA-PLA nanocomposites during cold sintering process: Influence of HA-to-PLA ratio and the plasticizing effect of PLA

Developing a nanocomposite that combines the stiffness of hydroxyapatite (HA), a bone-mimicking mineral, with the flexibility, and resorbability of polylactic Acid (PLA), a biodegradable polyester, presents significant potential in bone regeneration applications. The cold sintering process (CSP) offers a novel approach for consolidating HA-PLA composite at low temperatures, addressing the co-sintering challenge posed by higher consolidation temperatures requirement for HA compared to PLA’s compaction, or extrusion temperatures. This study investigates the effect of HA-to-PLA ratios and the plasticizing effect of PLA on the composite's consolidation behavior and mechanical properties, with a specific focus on HA consolidation within the PLA matrix under CSP conditions at 200 °C under 360 MPa pressure. Interestingly, the results revealed that the HA consolidation in composite matrix changes with PLA content and the plasticizing effect has a crucial role in enhancing this consolidation. An optimal HA-to-PLA weight ratio of 80:20 yielded superior HA consolidation and strong interfacial bonding between HA particles and HA and PLA, achieving an ideal mechanical strength and structural integrity balance. Overall, the HA-PLA composites exhibit mechanical strength comparable to human cortical bone, making them suitable for potential biomedical applications.