Abstract
To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR@-4368 (ADR). The FTIR (Fourier Transform infrared spectroscopy) analysis and SEM (scanning electron microscope) characterization demonstrated that the PLA molecular chain was bonded to the fiber surface and the epoxy-functionalized oligomer played a hinge-like role between the sisal fibers and the PLA matrix, which resulted in improved interfacial adhesion between the fibers and the PLA matrix. The interfacial reaction and microstructures of composites were further investigated by thermal and rheological analyses, which indicated that the mobility of the PLA molecular chain in composites was restricted because of the introduction of the ADR oligomer, which in turn reflected the improved interfacial interaction between SF and the PLA matrix. These results were further justified with the calculation of activation energies of glass transition relaxation (∆Ea) by dynamic mechanical analysis. The mechanical properties of PLA/SF composites were simultaneously reinforced and toughened with the addition of ADR oligomer. The interfacial interaction and structure–properties relationship of the composites are the key points of this study.
Highlights
Due to increasing concerns about environment and sustainability issues, natural fibers have attracted extensive attention for their renewable and sustainable nature
ADR oligomer played a hinge-like role between sisal fibers and PLA matrix during melt blending and processing, resulting in improved interfacial interaction between SF and the PLA matrix
The results indicated that the crystallization ability of composites declined and the viscoelastic response was enhanced with the addition of ADR
Summary
Due to increasing concerns about environment and sustainability issues, natural fibers have attracted extensive attention for their renewable and sustainable nature. To improve the interfacial interaction of natural fiber-reinforced polymer composites, many surface modification methods were applied to natural fibers to improve the compatibility between fibers and matrix [7]. It had been proved that chemical treatments of natural fiber surface were an effective way to improve the interfacial compatibility and adhesion of natural fiber-reinforced polymer composites [8]. Alkali treatment with sodium hydroxide has been widely used before other chemical treatment is performed in natural fibers surface modification to promote the interfacial interaction [18]. These chemical treatment methods could improve the interfacial adhesion of natural fibers and polymer matrices, but sometimes weaken the fiber strength itself at the same time. The interfacial interaction and structure–properties relationship of composites are key points of this study
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