Effect of nanoclay grafting onto flax fibers on the interfacial shear strength and mechanical properties of flax/epoxy composites

摘要

The low fiber strength and high hydrophilic characteristics limit the wide acceptance of natural fiber-reinforced polymer (NFRP) composites in structural applications. In this article, to enhance the mechanical properties of flax fiber-based NFRP, flax fibers were tried to be grafted with organic nanoclay in assistance of a silane coupling agent. The effects of the nanoclay grafting on the interfacial shear strength between flax-epoxy resin and the tensile and flexural properties of the flax-epoxy composites were investigated. Through micrograph observation (scanning electron microscope [SEM] and atomic force microscope [AFM]), together with Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis, nanoclay was confirmed to be successfully grafted onto the fiber surface through covalent bonds. The flax fiber-based NFRP plates were prepared with a vacuum-assisted resin infusion process. With the optimized nanoclay content (1.3 wt.%), an increase in the pull-out shear strength of flax yarn from epoxy block by 71% and short-beam shear strength by 17.9% were realized, respectively. Meanwhile, compared to the control samples, the grafted flax fiber-reinforced plates were enhanced in the flexural strength and tensile strength by 20.7% and 14.3%, respectively. POLYM. COMPOS., 40:3482-3492, 2019. (c) 2019 Society of Plastics Engineers