Press forming of short natural fiber-reinforced biodegradable resin: Effects of fiber volume and length on flexural properties

The effects of the volume fraction and length of natural fibers on flexural properties of biodegradable composites were investigated. Kenaf and bagasse were mixed with corn-starch biodegradable resin, and composite flexural specimens were fabricated by press forming. Cox's model that incorporates the effect of fiber compression in the cross section was applied to calculate the flexural modulus. Bagasse was found to be more compressible than kenaf due to the difference structure in the cross section. For up to 60% volume fraction kenaf and 66% bagasse composites, the flexural modulus increased with increase in fiber volume fraction, and these results were in good agreement with the calculated values. However, above 60% fiber volume fraction kenaf and 66% bagasse, the flexural modulus decreased due to insufficient resin. Moreover, the decrease of the flexural modulus occurred at fiber lengths 2.8 mm kenaf and 3.2 mm bagasse. Above these fiber lengths, there was no change in the flexural modulus of the composite specimens. This trend was also identified by the calculation.