Tensile behaviours of the coir fibre and related composites after NaOH treatment

Brown coir fibres were treated by NaOH solution with concentrations from 2% to 10% separately. Tensile strength of the alkali-treated fibres was measured. A decreased trend of the fibre tensile strength with increased NaOH density was found. Laminated coir fibre net was used as the reinforcement and polypropylene as the matrix to fabricate the composites with a heat press. The tensile strength of the samples was shown. In the case of NaOH density with 10%, lower tensile strength of the composite was noticed compared to the cases of 2%, 4%, 6% and 8%. This demonstrated that the fibre deterioration in the 10% case was serious. No significant difference was revealed in the composite tensile strength among the cases of 2%, 4%, 6% and 8%. This implied that the improved adhesive ability of the coir fibre with the matrix after the alkali treatment had been outweighed by the strength loss of the fibre in these four cases.