Improving the Interface Strength in Flax Fibre Poly(lactic) Acid Composites

In this study, the influence of four particular treatments on the mechanical properties of composites made from flax fibres and poly(lactic) acid is investigated. Unidirectional composite sheets with a fibre volume fraction between 30% and 50% have been produced using the film stacking method and then cut into specimens for tensile and three-point bending tests according to ASTM standards (D638 and D790). Samples using different matrix materials and fibre modifications have been manufactured using glycerol triacetate, thermoplastic starch, gamma-methacryloxypropyltrimethoxysilane (MS) and boiled flax yarn. For matrix modification, mass percentages of 3, 5 and 8% of glycerol triacetate or 5, 10 and 30% of thermoplastic starch were added to a commercially available grade (2002D) of poly(lactic) acid polymer. Chemical modification of flax fibres via silane treatment has been carried out using gamma-MS. As a more eco-friendly method of fibre treatment, boiled flax is also used in an attempt to achieve improved mechanical properties. The property results are presented along with differential scanning calorimeter and scanning electron microscope analyses examining the interfacial properties of the composite material.