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Effects of chemical modifications of pineapple leaf fibre on the properties of polypropylene composites

Olivia Ginikachukwu Nnodu, Isaac Ogbennaya Igwe, Michael Anayo Ojingwa, Chinedu Nwapa, Perpetua Ifeoma Oragwu, Samuel Nonso Okonkwo


The effects of chemical modifications of pineapple leaf fibre on the mechanical and end-use properties of pineapple leaf fibre filled polypropylene composites were studied within fibre content, 0 – 10 wt. % and particle size, 75 µm. The pineapple leaf fibre was alkali treated using sodium hydroxide (NaOH) and bleached using hydrogen peroxide (H2O2). Maleic anhydride-graft-polypropylene (MA - g - PP) was used as a compatibilizer. Analysis of the pineapple leaf fibre showed that it contains an appreciable quantity of cellulose (65.30 %) and has a density of 1.89 g/cm3, moisture content 6.10 %, oil absorption 1.96 g/100 g, ash content 1.94 %, and        pH 6.90. The pineapple leaf fibre composites were prepared in an injection moulding machine. Result showed that unfilled polypropylene exhibited higher tensile strength (39.17 MPa) than the filled polypropylene composites. The addition of MA - g - PP and the use of treated pineapple leaf fibres improved the tensile strength of the composites. The untreated pineapple leaf fibre prepared composites exhibited the least tensile strength and had higher elongation at break than the filled composites. The elongation at break of filled polypropylene composites decreased with increase in fibre content while the addition of MA – g - PP and treated pineapple leaf fibre improved the elongation at break of the composites. Generally, the hardness (BHN), specific gravity, and water absorption indices of the composites increased with increase in fibre content investigated. This study has shown that the use of MA - g - PP, alkali refined, and bleached pineapple leaf fibres in compounding polypropylene increased the hardness and specific gravity of the resulting composites and decreased their water absorption properties. These property improvements should justify the use of pineapple leaf fibre in processing polypropylene composites especially where the improved properties are of utmost consideration.


Polypropylene, composite, pineapple leaf fibre, tensile strength, water absorption, compatibilizer

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