Improved thermal and mechanical performance of ramie fibers reinforced poly(lactic acid) biocomposites via fiber surface modifications and composites thermal annealing

Ramie fibers reinforced poly(lactic acid) (PLA) biocomposites in the recent past have gained a lot of research attention for various applications due to their biodegradability, lightweight and renewable advantages. However, their low thermal stability performances and poor mechanical properties have to this date limited their industrial use. Herein, an approach to solve the two mischiefs is presented, which involved first surface modifying of ramie fibers followed by thermal annealing of the reinforced PLA biocomposites. The resultant biocomposites showed tunable mechanical and thermal resistance properties. These improved properties are ascribed to the improved interfacial bonding of the modified ramie fibers and PLA polymer, courtesy of newly introduced reactive groups onto fibers which were capable of building strong interface bonds between the polymer-fiber boundaries. More still, the thermal stability of the resultant composite is attributed to the thermal annealing condition which provided crystallized PLA molecules upon exposure to high temperatures and the steady cooling responsible for the increased degree of crystallinity in the composites as confirmed from X-ray diffraction and differential scanning calorimetric data results. Beyond ramie fibers-based composites reported herein, the presented methodology can also be extended to other natural plant fiber-based composites. These modifications are capable of providing better PLA/natural fiber-based composites for automobiles, electronics, and other related domains. (C) 2018 Society of Plastics Engineers