Engineering Poly(Lactic Acid)/Cellulose Nanocrystal Composites: A Comparative Review of Preparation Strategies and their Influence on Structure-Property Relationships

Abstract

The incorporation of cellulose nanocrystals (CNCs) into poly(lactic acid) (PLA) matrices has emerged as a promising approach to enhance the mechanical, thermal, and rheological properties of bioplastics. However, the final properties of PLA/CNC nanocomposites are dependent on the preparation methods employed. This review explores the impact of various synthesis techniques, including chemical grafting, melt processing, and solution-based approaches, on the dispersion, interfacial adhesion, and performance of PLA/CNC composites. While melt processing methods such as extrusion offer scalable production, they often lead to CNC aggregation, limiting reinforcement efficiency. In contrast, solution-based methods provide improved CNC dispersion but introduce challenges related to solvent removal and processing complexity. Recent advancements in reactive extrusion and surface-modified CNCs have demonstrated potential in mitigating these limitations. By comparing the effects of these preparation strategies on crystallinity, mechanical reinforcement, and rheological behavior, this review provides insights into optimizing PLA/CNC nanocomposite formulations for diverse applications, including packaging, biomedical devices, and additive manufacturing.