Flexural properties of treated and untreated kenaf/epoxy composites

In the current work, flexural properties of unidirectional long kenaf fibre reinforced epoxy (KFRE) composites are studied. The kenaf fibres were prepared into two types as untreated and treated (with 6% NaOH). The failure mechanism and damage features of the materials were categorized with the surface observation by scanning electron microscope (SEM). The results revealed that reinforcement of epoxy with treated kenaf fibres increased the flexural strength of the composite by about 36%, while, untreated fibres introduced 20% improvement. This was mainly due to the high improvement of the chemical treatment (NaOH) on the interfacial adhesion of the fibres and the porosity of the composites which prevented the debonding, detachments or pull out of fibres. For untreated KFRE, the fracture mechanisms were debonding, tearing, detachments and pull out of fibres. The developed composite exhibited superior properties compared to the previous composites based on natural and synthetic fibres.

Untreated kenaf fibre/epoxy composites. Treated kenaf fibre/epoxy composites.Figure optionsDownload as PowerPoint slideHighlights
► Treatment of kenaf fibres with 6% NaOH has improved the flexural properties of epoxy composites.
► Interfacial adhesion of the natural fibres is controlled by the microstructure of the fibres.
► Kenaf fibres have a potential to replace glass fibres for flexural applications.