Biocomposites Based on Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PHBHV) and Miscanthus giganteus Fibers with Improved Fiber/Matrix Interface.

Erica Rodi,Vittorio Sansalone,Thibault Lemaire,Valérie Langlois,Estelle Renard

doi:10.3390/polym10050509

Abstract

In this paper, green biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) and Miscanthus giganteus fibers (MIS) were prepared in the presence of dicumyl peroxide (DCP) via reactive extrusion. The objective of this study was to optimize the interfacial adhesion between the reinforcement and the matrix, improving the mechanical properties of the final material. To this aim, two fibers mass fractions (5 and 20 wt %) and two different fiber sizes obtained by two opening mesh sieves (1 mm and 45 μm) were investigated. The impregnation of fibers with DCP before processing was carried out in order to promote the PHBHV grafting onto MIS fibers during the process, favoring, in this way, the interfacial adhesion between fibers and matrix, instead of the crosslinking of the matrix. All composites were realized by extrusion and injection molding processing and then characterized by tensile tests, FTIR-ATR, SEM, DSC and XRD. According to the improved adhesion of fibers to matrix due to DCP, we carried out an implementation of models involving that can predict the effective mechanical properties of the biocomposites. Three phases were taken into account here: fibers, gel (crosslinked matrix), and matrix fractions. Due to the complexity of the system (matrix–crosslinked matrix–fibers) and to the lack of knowledge about all the phenomena occurring during the reactive extrusion, a mathematical approach was considered in order to obtain information about the modulus of the crosslinked matrix and its fraction in the composites. This study aims to estimate these last values, and to clarify the effect caused by the presence of vegetal fibers in a composite in which different reactions are promoted by DCP.

Highlights

In recent years, the attention of both academia and industry was focused on eco-friendly materials from renewable resources, due to the growing concern over environmental issues
We proposed an approach based on the reactive grafting initiated by dicumyl peroxide (DCP), in order to improve the adhesion of Miscanthus fibers to a PHBHV matrix, with a consequent improvement of the mechanical properties of the final composite
ΦGG for for composites composites PHBHV. This result indicates that the crosslinking phenomenon within the matrix is predominant when compared to the grafting fibers. by DCP via reactive extrusion led to the improvement of the

Summary

Introduction

The attention of both academia and industry was focused on eco-friendly materials from renewable resources, due to the growing concern over environmental issues. The pollution caused by non-biodegradable synthetic plastics led to the investigation of totally biobased polymers that could replace the first ones [1,2,3,4,5,6,7]. A class of polyesters of great interest is microbial polymers known as poly(3-hydroxyalkanoate)s (PHAs). This family of polymers is known for the good biodegradability and biocompatibility, being derived from bacterial synthesis [8,9,10]. Polymers 2018, 10, 509 for a wide range of applications, starting from biomedical, such as for tissue engineering and bone replacement, to packaging, agriculture, and personal disposal articles [8,11,12,13].

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