Natural fibres have shown immense potential as reinforcement for composites in the place of conventional fibres. Natural fibres are lightweight, cheap and environmentally friendly. However, it is already established that natural fibres have poor interaction with polymers due to its hydrophilic nature, resulting in poor interfacial adhesion, which is detrimental to the properties of the composite. Chemical surface treatment has been done to improve the interfacial adhesion. Various concentrations of sodium hydroxide (NaOH) and soaking times were employed, and the treated fibres were then characterized using thermogravimetric analyser, X-ray powder diffraction and Fourier transform infrared (FTIR) spectrometer. Single-fibre tensile tests were done on selected samples. The surface of the fibre was analysed with field-emission scanning electron microscope to study the surface morphology of the treated and untreated fibres. Generally, the treated fibres have higher thermal stability compared to untreated fibres. However, no significant trend was observed as a result of varying NaOH concentration and soak time. It was also observed that kenaf fibres treated with 4% (w/v) NaOH for 5 h exhibited the highest tensile modulus and tensile strength compared to other treated fibres. Impact properties of composites prepared from untreated and NaOH-treated kenaf were tested to confirm the finding, and it was determined that the treated kenaf composites have superior impact properties to its untreated counterpart.
In this paper, the mechanical performance of resin transfer moulded nonwoven kenaf fibre/epoxy composites in the fibre volume fraction ( V f) range of 0–0.42 was investigated. The effect of the needle-punching direction on the tensile properties of the composites was also investigated. The highest tensile, flexural and fracture properties were attained at a V f of 0.42. The nonwoven kenaf fibre/epoxy composites were proven to exhibit tensile isotropy. The typical load versus displacement graph and scanning electron microscopy micrographs of the epoxy and nonwoven kenaf fibre/epoxy composites revealed that the energy absorbing events caused by the fibres led to improvements in the fracture toughness. Meanwhile, the micromechanical parameters of the composites were determined by a micromechanics analysis using the Cox–Krenchel model. The analysis proved the applicability of the model for nonwoven kenaf fibre/epoxy composites as the calculated efficiency factors were comparable to the values from previous literatures.
In this work, nonwoven kenaf fibre/epoxy composites were produced by using resin transfer moulding. The effect of kenaf fibre volume fraction on the composites’ tensile properties and Poisson’s ratio was investigated. Experimental results show that highest tensile properties and Poisson’s ratio were attained at volume fraction = 0.42. A simple method has been developed to predict the fibre transverse modulus and has allowed the characterisation of kenaf fibre’s elastic anisotropy. The performance of the Tsai–Pagano model in predicting the composites’ tensile modulus and Poisson’s ratio was compared with the Manera and Cox-Krenchel model. Results showed that the consideration of fibre’s elastic anisotropy in the Tsai–Pagano model yielded a good prediction of both composites’ modulus and Poisson’s ratio. Meanwhile, the Bowyer–Bader model produced a better tensile strength prediction owing to the inclusion of fibre length and orientation factors in the model.
PLA nanocomposites containing 2 wt% of OMMT clay were prepared using twin screw extruder followed by injection moulding. EPR-g-MAH (5–20 phr) was used to improve the impact properties of PLA/OMMT nanocomposites. The mechanical properties of PLA nanocomposites were studied through tensile, flexural and impact tests. The morphology and dispersion of OMMT were examined using TEM and XRD. The thermal properties were characterised using differential scanning calorimetry and thermogravimetric analysis. The impact strength and thermal stability of the PLA/OMMT nanocomposites were improved significantly in the presence of EPR-g-MAH. The degree of crystallinity of PLA/OMMT was influenced by the loading of EPR-g-MAH. TEM and XRD results revealed the formation of PLA nanocomposites as the OMMT was exfoliated in the presence of EPR-g-MAH.
Biodegradable poly(butylene succinate)/organo-montmorillonite nanocomposites were prepared at different organo-montmorillonite loadings, using maleic anhydride-grafted poly(butylene succinate) as compatibilizer. Poly(butylene succinate) nanocomposites were exposed to outdoor natural weathering for 180 days. Weight loss and decrease in mechanical properties after weathering revealed the degradation of poly(butylene succinate). Natural weathering caused photo-oxidation on poly(butylene succinate), leading to the formation of degraded products, as manifested in Fourier transform infrared spectroscopy. Gel permeation chromatography showed a significant reduction in molecular weight after weathering. It was noted that poly(butylene succinate) nanocomposite exhibited lower degradability as compared to neat poly(butylene succinate), due to the enhanced barrier properties after the addition of organo-montmorillonite. However, the incorporation of maleic anhydride-grafted poly(butylene succinate) increased the degradability. Degree of crystallinity of poly(butylene succinate) reduced after weathering, as shown in differential scanning calorimetry. Scanning electron microscopy analysis revealed fungal and bacterial colonization on the sample surface. In addition, the isolation and identification of bacterial strain were also performed.
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