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Li, Zeshi

University of British Columbia

While natural fiber composites have lower environmental impact and improved lifecycle and cost compared to synthetic carbon and glass fiber composites, they have the drawback of lower compatibility and reduced interfacial properties with the polymer matrices, which have detrimental effects on composite behavior. To alleviate this, improvements are seen in natural fiber composite material properties following surface treatment methods such as NaOH and graphene oxide (GO) treatments in past studies. This study conducts a parametric analysis on flax fibers and flax fiber composites treated with combinations of NaOH and GO to determine the effect of GO treatment on fibers in the absence of the epoxy matrix. GO characterization was performed with X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Flax fibers treated with NaOH at concentrations between 0.5-4% for durations between 1 h and 24 h, and dip-coated in GO with concentrations ranging between 0.2-1% for durations between 30 mins and 2 h to determine degree of improvement on single fibers. Tensile testing and microbond testing were performed on single fibers to assess the tensile properties and interfacial shear strength, resulting in significant increases in tensile strength. GO-treated flax/epoxy composites were prepared at optimal conditions identified through single fiber tests and tested to failure on an Instron tensile tester to evaluate the degree of improvement at the composite level. SEM was used for failure analysis to determine the mode of failure and digital image correlation (DIC) was used to obtain full-field mapping of the deformation behavior of the produced composites as well as accurate values for strain. Results indicated that 0.2% GO 2h treatment significantly increases the tensile strength and modulus of flax-epoxy composites compared to control samples, but no significant consistent change to the tensile strength, modulus, or interfacial shear strength of individual fibers was observed. This study provides insights into the properties of GO, improving material properties of natural fiber composites through NaOH and GO pre-treatment, and the mechanisms and interactions that cause GO to be effective in acting as a reinforcer for composites.

Text

2024-08-27

Attribution-NonCommercial-ShareAlike 4.0 International

http://hdl.handle.net/2429/89037

Materials Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-sa/4.0/