Abstract:
Flax fibres have shown promise as a suitable ‘green’ alternative to glass fibres. Their specific strength and specific stiffness is similar to that of E-glass fibres. However, to date, composites manufactured with flax fibres have typically had lower specific strengths than glass-fibre composites. There is also only limited information available on the performance of high volume-fraction (>50%) flax/epoxy composites, which is the range of volume-fractions likely to be used in high performance applications. This study compares the quasi-static tensile and compressive mechanical properties and dynamic impact performance of high volume-fraction flax/epoxy and glass-fibre laminates manufactured using Resin Transfer Moulding (RTM). Panels were manufactured from woven 150gsm flax and 285gsm glass fibres with Gurit Prime 20LV Epoxy resin. Two different comparisons were made. The first was between 4mm thick flax/epoxy and glassfibre panels each with 20 layers and hence the same number of interfaces between lamina. These interfaces are where delamination can occur, so are important for impact performance. The second case compared two panels having the same areal weight; a 6 mm flax/epoxy panel and a 4 mm glassfibre panel with 32 and 20 plies respectively. As flax fibres have a lower density than glass fibres, panels of the same weight are thicker which may provide an advantage for out-of-plane properties, such as impact and flexural strength. Results from this study indicate that flax-fibre laminates, even on a specific basis, have a lower tensile, compressive and impact performance than thickness or weight equivalent glass-fibre laminates. Potential improvement may be seen by combining glass and flax fibres into a hybrid laminate to leverage the sustainability and lower density of flax fibres.
