Effect of bamboo fiber length in opened cell foam core sandwich composite on water absorption and their mechanical properties

Abstract

The objective of this paper is to determine the density, water absorption characteristics, tensile strength, edgewise and flatwise compressive strength and bending strength of sandwich composite with opened cell bamboo fiber foam as core. To manufacture opened cell bamboo fiber core, the lengths of bamboo fiber were varied from 10 mm to 40 mm, with an increment of 10 mm. The fiber volume fraction was kept constant at 15% (by volume). Unsaturated polyester was used as a binder of bamboo fibers. Around 3 mm in thickness of plywood was used as skins of the sandwich composite. The physical and mechanical testing were carried out such as density (ASTM C271), water absorption (ASTM C 272), tensile test (ASTM C 297), edgewise compressive test (ASTM C364-99), flatwise compressive test (ASTM C365-05) and bending test (ASTM C392). The results showed that the density of sandwich composite is not associated with fiber length, which is about 0.45 g/cm3. The water absorption capability showed an increase in line with the fiber length. The tensile strength tends to increase in line with the fiber length. The optimum edgewise compressive strength was obtained at the fiber length of 30 mm, however the effect of fiber length on the flatwise compressive strength is insignificant. Up to the fiber length of 20 mm, the bending strength of sandwich composite tends to increase, but then it tends to be flat at fiber length of 20-40 mm.