Green composites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and sugarcane bagasse fibers plasticized with triethyl citrate: Thermal, mechanical and morphological properties

Abstract

In this work, PHBV composites were prepared by melting extrusion using triethyl citrate (TEC) as a biodegradable plasticizer and sugarcane bagasse fibers (SBF) as reinforcement. The plasticizer TEC played a crucial role in the preparation of the formulations by extrusion, reducing the viscosity of the melt and minimizing the thermomechanical degradation of PHBV. Moreover, TEC was an efficient plasticizer for the composites, reducing the glass transition and melting temperatures of PHBV and making the specimens ductile. The increase in the concentration of TEC led to an enlargement of the interlamellar spacing and larger PHBV spherulites without changing the cell parameters. In contrast, the introduction of the SBF elevated the viscosity of the molten during extrusion, leading to thermomechanical degradation of PHBV. The SBF acted as a nucleation agent for the PHBV crystallization and oriented the growth of the PHBV crystals due to the transcrystallization, which contributed to the matrix-filler adhesion, the increase in the lamellae thickness, and changes in the thermal properties of PHBV. The SBF acted as a reinforcing agent, increasing the tensile properties of the matrix. Therefore, TEC and SBF had antagonistic effects on the properties of the formulations, opening opportunities to tune their properties by varying the composition.