Cross-sectional area evaluation and tensile properties of alkali-treated kenaf fibres

A cross-sectional area evaluation method for multi-cell type natural fibres treated in a highly concentrated alkali solution was proposed using kenaf fibres. Cross-section of kenaf fibres was drastically changed by the alkali treatment compared to the untreated fibres. Conventional data-based approximation (DBA) method for evaluating cross-sectional area was not sufficient, because it was based on cross-sectional area data of the untreated fibres. DBA was modified on the assumption that the shape of each cell in the alkali-treated fibres was an ellipse, and again correlated with hexagonal cross-sectional area, which was approximated by measuring the projection widths on the fibre along 0°, 60° and 120° directions. This is the new data-based approximation method (DBA-AT). Results showed that the tensile strength was greatly improved, compared to the strength values estimated by untreated fibre-based DBA. Especially, tensile strength of alkali-treated fibre on the condition of 15 wt%NaOH for 1 h was comparable to untreated fibre.