Effects of alkali treatment on properties of bamboo fiber and bamboo fiber reinforced polypropylene composites

In order to investigate the effect of bamboo fiber energy on adhesion work between fiber and resin and the interface of composites, the surface of bamboo fiber was modified by alkali treatment, then bamboo fiber reinforced polypropylene(PP) composites were prepared by means of compression molding technology. The effects of alkali treatment on properties of bamboo fiber, the adhesion work between bamboo fiber and PP and the mechanical properties of bamboo fiber/PP composites were studied. SEM was used to describe bamboo fiber surface morphology change after different concentration of alkali treatment. The results reveal that with the increase of the concentration of alkali, bamboo fiber strength shows some fluctuations, while at the alkali concentration of 1wt%, bamboo fiber strength reaches the maximum value. The adhesion work between bamboo fiber and PP is closely related to bamboo fiber polarity ratio. The smaller polarity ratio is, the bigger adhesion work becomes. With the increase of the concentration of alkali, the adhesion work between bamboo fiber and PP resin and shear properties of bamboo/PP composites show the same trend, and both of them attain optimal level at the alkali agent concentration of 20wt%. Compared with untreated bamboo fiber, the adhesion work between bamboo fiber and PP resin increases by 67.18%, while bamboo fiber/PP composite's shear properties increase by 23.29%. While at the alkali agent concentration of 5wt%, the flexural strength of the bamboo fiber/PP composites attains optimal level, which is 23.13% higher than that of untreated.