Characterisation of Elementary Kenaf Fibres Extracted Using HNO₃ and H₂O₂/CH₃COOH

In this study, elementary kenaf fibres were separated from fibre bundles using two different treatments. The first involved treating with nitric acid (HNO₃) while the second used a mixture of hydrogen peroxide (H₂O₂) and acetic acid (CH₃COOH). Both treatments were successful in isolating the elementary fibres but the H₂O₂/CH₃COOH gave a better fibre yield and required a shorter treatment time. The fibres treated with HNO₃ had an average length of 0.2 mm, an aspect ratio of 15 and a defect density of 21 defects per mm. In contrast, the H₂O₂/CH₃COOH treated fibres had a length of 2.3 mm, an aspect ratio of 179 and a defect density of 14 defects per mm. Both treatments removed lignin, pectin, and waxes. They also increased cellulose crystallinity in the fibres, especially for HNO₃ treatment. However, they resulted in some oxidation of cellulose. The H₂O₂/CH₃COOH treatment gave a substantial improvement in the thermal stability of the fibres while a marked decrease was observed for the HNO₃ treatment.