The Importance of Fiber/Matrix Adhesion and Annealing Process in Water Uptake of PLA/PMMA Matrix Composites Reinforced with Sisal Fibers: The Effect of Coupling Agent Addition

With the aim to open new applications possibilities to novel biocomposites based on PLA/PMMA matrix and reinforced with sisal fibers, it was studied the effect of water immersion aging on biocomposite tensile properties. In the current study it was evidenced the importance of the annealing process and fiber/matrix adhesion on the mechanical performance of composites after immersing in water for around 7 months. The presence of the copolymer and the annealing process led to the minor extent of damage of mechanical properties of prepared biocomposites. Results obtained in the current study suggested that although the amount of copolymer incorporated in composites was low, the presence of copolymer is crucial to improve fiber/matrix adhesion and consequently the mechanical performance of composites after immersing in water. It was observed that even though the water uptake damaged the interfacial adhesion, leading to the tensile strength reduction; however, annealed composite with 30 wt% of fiber and modified with the copolymer showed a strength value of around 53.5 MPa. It must highlighted that even though water aged for 7 months, the annealed composite with copolymer showed yet a higher strength value than dried commercial mineral-filled PP composites reported in the literature.