Effects of enzymatic treatment of sisal fibres on tensile strength and morphology

Abstract

Abstract This study explored the use of enzymes as an alternative method of hydrolysing cementing layers in sisal fibres. Sisal fibres were treated with sodium hydroxide (NaOH) and hemicellulase enzyme and the effects of treatment on the morphology and tensile strength were examined. Pre-treatment was done using organic solvents to remove phytochemicals including chlorophyll. The 3,5-Dinitrosalicylic acid (DNS) test was used to confirm enzymatic activity as well as to optimise the hydrolysis treatment where 5% Hemicellulase at pH 4.6 gave the best results. Other fibres were treated with 5% NaOH for comparison. Physical properties of raw and treated fibres were analysed using the Fourier Transform Infra-Red (FTIR) spectroscopy to determine surface chemical modifications, Scanning Electron Microscopy (SEM) for morphological changes and the Instron Tensile Tester for tensile stress and strain. The NaOH treated fibres had slightly different functional groups, whereas the enzyme treated were identical to the control sample. The hydrolysis of the cementing layer was also observed from SEM images as some peeling of cementing layer was observed after hydrolysis by both NaOH and hemicellulose. The tensile strength of the fibres decreased after hydrolysis and NaOH treated fibres had the lowest tensile strength followed by enzyme treated fibre.