Effect of Chemical Treatments on Coir and Banana Fibres for Effective Pulverization to Fibrous Particles

The effect of chemical treatment on the surface modification and pulverization of coir and banana fibres was investigated in this study. Caustic soda, silane, and potassium permanganate treatments were chosen to remove the non-cellulosic contents (i.e., lignin, hemicellulose, wax, etc.) as well as to improve the pulverization of banana and coir fibres during the ball milling. Surface morphology and mechanical characteristics of coir and banana fibres were compared before and after the chemical treatments. The chemical treatment was found beneficial for the easier defibrillation of banana and coir fibres during ball milling. Among all the chemical treatments, the silane treatment was found more effective to get smaller size of particles with narrow particle-size distribution. This behaviour was attributed to the hydrophobic characteristics of the silane-treated fibres, which pulverized effectively to particles without forming fibre lumps rolling inside the milling container. The approximate particle size of untreated coir fibres was 2200 nm, which reduced to 788 nm with NaOH treatment, 413 nm with KMnO4 treatment, and 496 nm with silane treatment after 90 min of pulverization. Similarly, the particle size of untreated banana fibres was 922 nm, which reduced to 777 nm with NaOH treatment, 426 nm with KMnO4 treatment, and 223 nm with silane treatment.