Mechanical characterisation of a bamboo fibre/polylactic acid composite produced by fused deposition modelling

Polymer matrices are usually reinforced with fibres giving a good strength/weight ratio. Currently, innovative research has been focussed in producing new composite materials using natural fibres as an alternative sustainable material. In the present work, the mechanical behaviour of a composite based on polylactic acid reinforced with bamboo fibre produced by additive manufacturing was evaluated. Specimens were manufactured using fused deposition modelling with different geometry depositions, layer thicknesses and fill densities. The results were evaluated performing an analysis of variance with a confidence level of 95%. The composites were subjected to mechanical testing to evaluate the influence of process parameters in tensile strength, strain, and elastic modulus. It was observed that the principal factors that influence the elasticity are the deposition geometry and fill density. Fracture zones and manufacturing defects were additionally studied using optical and scanning electron microscopy. The vertical orientation of the layers causes the premature rupture of the test samples due to the tension being reverted at the interface between the layers. The specimens showed slight adhesion between the polylactic acid matrix and the bamboo fibres. This effect was related with the presence of porosity, cracks and local deformations in the composite material.