Toughened Sustainable Green Composites from Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Based Ternary Blends and Miscanthus Biofiber

Abstract

Novel green composites with an excellent balance of properties were successfully fabricated from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) based renewable ternary blends and miscanthus through a cost-efficient reactive extrusion process. The ternary blend of PHBV with poly(butylene adipate-co-terephthalate) (PBAT) and epoxidized natural rubber (ENR) was engineered as a high toughening matrix for the natural fiber composites using dicumyl peroxide (DCP) as the reactive compatibilizer. The addition of miscanthus fibers into the matrix significantly enhanced its stiffness and thermal resistance while still keeping a good toughness. A high value of impact strength up to 240.5 J/m was still achieved even with 20 wt % miscathus added. The mechanical modulus of the composites were also analyzed using mathematical models including rule of mixtures (ROM), inverse rule of mixtures (IROM), and the Tsai–Pagano equations. In the multiphase blends and composites, ENR played unique dual roles as an effective coupling agent and impact modifier in the presence of DCP. Scanning electron microscopy (SEM) results indicated good interfacial adhesion among the different phases in the composites, which played a vital role in improving the strength and toughness of the materials. At the same time, balanced melt viscosity and density were also achieved for the composites, which are important for wide application.