Composite of short coir fibres and natural rubber: effect of chemical modification, loading and orientation of fibre

Coir fibre is considered to be a poor reinforcing fibre in rubber because of its low strength and lack of physical characteristics that are essential for a reinforcing fibre. Interfacial adhesion between coir and natural rubber (NR) was improved by treatment of the coir fibres with alkali (sodium hydroxide and sodium carbonate) and NR solution, and by the incorporation of HRH/RH bonding systems. Composites containing 10 mm long coir fibres were vulcanized at 150 degrees C according to their respective cure times. Green strength measurements were carried out to measure the extent of fibre orientation. The effectiveness of green strength measurements in finding the degree of fibre orientation was also analysed. Tensile modulus, tensile strength and tear strength of the composites were analysed to investigate their performance. Anisotropic swelling studies were conducted to investigate the extent of fibre orientation and the fibre/rubber interfacial strength. Scanning electron microscopy was performed to study the fibre topology. (C) 1997 Elsevier Science Ltd. All rights reserved.