Effect of alkali treatment on the flexural strength of bamboo fibers reinforced styrofoam-modified polyester resin

Abstract

Bamboo fibers are one of the abundant resources of natural fibers used for reinforcing polymer. Bamboo fiber is a candidate for replacing synthetic fibers such glass and carbon fibers as it has a specific strength that is comparable with glass fiber and is also biodegradable. However, generally the compatibility of natural fibers with polymer matrix is poor and it is necessary to improve the fiber-matrix interaction. The paper presents the effects of alkali treatment on the flexural strength of bamboo fibers reinforced styrofoam-modified polyester resin. Bamboo fibers were treated using alkali (NaOH) solution with concentrations of 4, 8 and 12% (by weight). The treatment time variation was 0.5, 1 and 2 hours in two different temperatures; room and elevated temperatures (50°C). The results show that the alkali-treated bamboo fibers/modified polyester composites has better performance that the untreated bamboo fibers. In room temperature, in general the flexural strength increases with increasing alkali concentration, but the increase depends on the treatment time. At a relatively short treatment time (i.e. 0.5 hour), the flexural strength increases with increasing the alkali concentration. However, at relatively longer treatment times (i.e. 1-2 hours), the flexural strength reaches an optimum at an alkali concentration of approximately 8%. At elevated temperature, however, it seems that the optimum flexural strength is obtained at a concentration of approximately 4% rather than at a concentration of 8% at a room temperature treatment, for all treatment times. Compared to the untreated bamboo fibers, the optimum flexural strength of the treated bamboo fibers/modified polyester composites increases by approximately 90%.