Characterization of water absorption properties of a partial bio-composite made from cotton stalk fibres and phenol formaldehyde resin

Abstract

Cotton stalks are a by-product of cotton farming and about two to three tonnes of cotton stalks are generated per hectare of land farmed. In this research, fibres extracted from waste cotton stalks using natural retting and decortication were used to fabricate a bio- composite. Normally, these wastes are disposed of on the farmland through incineration thus polluting the air through emission of harmful greenhouse gases. In accordance with sustainable development goals, there is a need to sustainably manage forests and combat desertification which can be better achieved through intensification and greater use of agricultural by-products. This can be achieved by using waste cotton stalks to make fibreboards as a replacement material for some solid wood applications. Cotton stalks are agricultural waste generated after cotton harvesting and tend to harbour parasites such as the pink bollworm and destructive polyphagous mealybug when left on farmland. Hand layup technique was used to fabricate the partial bio-composite. The cotton stalk fibre mass fraction (M f ) varied across five levels between 10.96% – 38.11%. The fabricated composite was subjected to water absorption tests which was carried out at intervals of 2, 4 and 24 hours. Regression analysis was carried out using Minitab software to ascertain effect of varying fibre content on water absorption. Composite density was maintained between 644 - 1004 kg/cm 3 . The water absorption varied from 64.94% to 94.97% increasing with fibre loading due to the hydrophilic nature of the cellulosic cotton stalk fibres for the first two hours of the composites being submerged in water thereafter followed by a period of very slow and consistent water uptake. The developed composite compared well to standards and proved to have suitable properties that give it potential end uses in partition boards, and for furniture applications.