ISOLATION OF CELLULOSIC NANOPARTICLES FROM COIR FIBRE FOR THE PREPARATION OF NATURAL RUBBER COMPOSITES

Abstract

Coir fibre and natural rubber are renewable and sustainable agro-resources that can be harnessed for the production of finished rubber articles on industrial scale. In this research, coir fibres extracted from coconut husk were subjected to alkaline-peroxide delignification. The delignified fibres were further transformed into coir fibre cellulosic nanoparticles (CFNP) with particle size distribution of 68–311 nm and a polydispersity index (PDI) of 0.371 through friction homogenization. These particles were subsequently used as reinforcement material in the preparation of vulcanized natural rubber composite through melt intercalation process using two roll mixing mill and shaped/vulcanized through compression moulding process. Tensile strength increased from 1.85 to 3.82 MPa as CFNP loading was increased from 0 to 25 parts per hundred rubber (pphr) representing 112% reinforcement. Tensile moduli at 100 and 300% of elongation were also found to increase with increasing CFNP loading; however, slight increase in water absorption with increasing CFNC loading were also observed. Thermo-gravimetric analysis (TGA) also revealed that the addition of 25 pphr of CFNC shifted the onset degradation temperature of reference neat NR matrix from 270 to 258°C. Therefore coconut husk cellulosic nanoparticles could be a suitable feed stock for rubber reinforcement on industrial scale.

Keywords: Cellulosic nanoparticles, alkaline-peroxide delignification, thermogravimetric analysis, water absorption