Microstructure and Sorption Properties of Alkaline Surface Modified Coir Bio Fibre

Abstract

Natural fibres have attracted the attention of researchers and scholars due to its advantage over conventional fibres. Coir fibre is a natural bio fibre extracted from coconut plant with the advantage of low cost, low density, specific tensile properties, renew-ability, recyclability; bio-degradability and is non abrasive to the equipment. It contains lignin, hemicellulose, wax and cellulose. The hydrophilic nature of bio fibres poses a challenge in utilisation as reinforcement for structural applications in concrete, mortar and polymer. It has however been found in recent times to be an effective reinforcement material in cement and phenolic matrices when subjected to better surface that modifies its hydrophilic nature. This paper presents an investigation into the alkali surface treatment of coir fibre and its effect on the cleanliness of the surface from dirt and fibre sorption characteristics. The natural fibre was treated by immersion in varied NaOH concentration (0 to 20% at 2.5% step increment) of sodium hydroxide solution (NaOH) for varied period of 6 hrs. interval up to 108 hrs. The specimens were also examined for morphology and microstructure properties using the scanning electron microscopy (SEM). The SEM micrograph revealed the specimen treated in 10% NaOH concentration at 24 hours of immersion period as having the smoothest surface and most cleaned. The examined sorption characteristics of the treated fibres further affirm that the water absorption became relatively stable for all specimen after 24 hrs and optimum within the 24 to 48 hrs treatment, while lowest absorption for the fibre treated in 10% NaOH being a value 383% at both 54 hrs and 72 hrs.