In this article, the effect of alkali treatment (with 5 wt. % sodium hydroxide solution for 30 min) on the compressive,
in-plane shear, impact properties and vibration characteristics of flax- and linen-fabric reinforced epoxy composites was
investigated. Test results show that alkali treatment enhanced the compressive strength and compressive modulus,
in-plane shear strength and shear modulus, and specific impact strength of both flax- and linen-epoxy composites.
However, after the treatment, the impact strength and damping ratio of the flax and linen composites decreased. The
reduction in impact strength and damping ratio is believed to be attributed to the improved fibre/matrix interfacial
adhesion, as analysed by scanning electron microscope.