Mechanical, hygrothermal ageing and moisture absorption properties of bamboo fibers reinforced with polypropylene composites

Bamboo fibers reinforced with non-woven fabric polypropylene composites were prepared via compression molding. Three types of bamboo fibers were used in the research: untreated, treated with a sodium hydroxide solution and treated with a sodium hydroxide solution followed by three-aminopropyltriethoxysilane. The effects of the preformed structures and chemical treatments on the composite performances were investigated. The results showed that the composite attained optimum mechanical properties at an alkali concentration of 5% and at a silane coupling reagent concentration of 3%. The preformed structure composed of materials with bamboo fiber/polypropylene mass ratios of 50/50 and 70/30 exhibited ideal mechanical properties. The moisture absorption behavior of the composites with different bamboo fiber contents exhibited good agreement with Fick’s law. Scanning electron microscopy showed that the composites prepared using alkali-silane-treated fibers demonstrated better bonding between the fibers and matrix and had fewer voids in the composites. We also confirmed that the modifications of the bamboo fibers improved the hygrothermal properties of the composites because of the improved interfacial adhesion between the fiber and matrix.