Effect of agave fiber content in the thermal and mechanical properties of green composites based on polyhydroxybutyrate or poly(hydroxybutyrate-co-hydroxyvalerate)

Abstract

In this study, agave fibers which are an important waste product of the Tequila industry are evaluated for the production of green biocomposites prepared with two biopolymers: polyhydroxybutyrate (PHB) and its copolymer with hydroxyvalerate P(HB-HV). The biocomposites were produced by compression molding with two main objectives: (1) to reduce the amount of biopolymer (due to its high cost) in the final piece and (2) to improve the mechanical properties of the material. In order to evaluate the effect of fiber content over both biopolymers, three agave fiber contents were used (10, 20 and 30wt%) to prepare them. Afterwards, a comprehensive thermo-mechanical characterization was performed. The results showed that the addition of agave fiber (30wt%) to both matrices enhances their tensile modulus by 80 and 50% in comparison with PHB and P(HB-HV) respectively, while for their flexural modulus the increase was 36 and 41% respectively. Additionally, tensile and flexural strength were not affected negatively while a significant increase in impact strength was obtained (44 and 66% respectively for biocomposites containing 30wt% of agave fiber in comparison to PHB and P(HB-HV) matrices). The results show a significant positive role of agave fibers on behalf of moduli reinforcement and toughening for these brittle biopolymers.