The effects of alkali treatment on the mechanical and chemical properties of pineapple leaf fibres (PALF) and adhesion to epoxy resin

The focus of this study was to obtain the optimum alkaline treatment for pineapple leaf fibre and its effect on the mechanical and chemical properties, surface topography, heat resistivity, as well as its interfacial bonding with epoxy matrix. There were 6 different treatment conditions set for the fibre. The morphology of a single fibre observed under the Digital Image Analyzer indicates slight reduction in fibre diameter with increasing NaOH concentration. The Scanning Electron Microscope (SEM) results show the deteriorating effect of alkali, which can be seen from the removal of impurities and increase in surface roughness. The mechanical analysis indicates that 6% NaOH treatment with 3-hour immersion period yielded the highest tensile strength. The adhesion between single fibre and epoxy resin was analysed through the micro-droplet test. Alkaline treatment results in better mechanical bonding between fibre and epoxy resin. It was found that 6% NaOH treatment with 1-hour immersion yielded highest interfacial shear stress. However, as NaOH concentration went above 6 %, the fibre started to show reduction in mechanical properties, as well as fibre-matrix interlocking. The TGA analysis implies that alkaline treatment improved the thermal stability and heat resistivity of the fibre. (paper)