Water Absorption and Impact Strength of Alkali-Treated Bamboo Fiber/Polystyrene-Modified Unsaturated Polyester Composites

Abstract

ABSTRACT The paper presents the water absorption, swelling strain and the impact strength of alkali-treated bamboo fiber/polystyrene-modified unsaturated polyester (MUP) composites. The bamboo fibers were treated using alkali (sodium hydroxide) solution at the concentrations of 4, 8 and 12wt.% with the treatment times of 0.5, 1 and 2 hours under room (28oC) and elevated temperatures (50oC). The impact strength was investigated under dry and wet conditions. Under room temperature treatment, the equilibrium water uptake tended to decrease with the increase of alkali concentration; however, the diffusion rate did not indicate a clear trend. Meanwhile, the swelling strain tended to increase with the increase of alkali concentration. Under elevated temperature treatment, the water absorption of bamboo fiber/MUP composites further reduced, compared to that of under room temperature treatment at the same concentration. In dry condition, under both temperature treatments, the impact strength of the treated bamboo fiber/MUP composites was lower than that of the untreated bamboo fiber/MUP composites; however, the treatment under elevated temperature improved the impact strength, compared to that of under room temperature treatment. In wet condition, under both temperature treatments, the impact strength of the treated bamboo fiber/MUP composites improved and again the treatment under elevated temperature had the better improvement than the treatment under room temperature.