Effect of Alkaline Pre-Treatment on the Surface Modification of Napier Grass Fibres for the Properties of Medium Density Fibreboard (MDF)

Abstract

In this study, Napier grass (Pennisetum purpureum) fibres which hold 59.19% cellulose, 21.35% hemicellulose and 7.26% lignin were comprehensively characterized to evaluate their potential as building material for medium density fibreboard (MDF). The purpose of this work was to examine the effects of sodium hydroxide solution as an alkali pre-treatment in determining the best condition for lignin removal in Napier fibres. The treatments were conducted using NaOH concentrations of 0.5, 3.0, 5.5, 8.0, 10.0 and 10.5 wt. %. The morphology of the fibres was observed using scanning electron microscope (SEM) and its chemical compositional changes was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. The study showed that the morphological observation demonstrated that the best concentration for the removal of lignin in Napier fibre was 10.5 wt. % NaOH solutions. It has been found that as the alkali concentration increased, the surface of the fibre becomes rougher which reduced the void content in the fibres. The fibres that were alkali-treated using NaOH solutions of various concentrations as well as the untreated one were subjected to single fibre testing. From the results of the single fibre testing, it is revealed that the 10.5% alkali-treated Napier grass fibres yielded the maximum and highest strength. This further signifies that alkali pre-treatment has significant impact on the production of MDF board from the non-wood fibres biomass such as Napier fibre.