Studies on tribological behaviour and dielectric properties of bio-fiber reinforced composites

Abstract

Within the last forty years there has been a rapid increase in the production of synthetic composite, those incorporating fibres in various plastics (polymer) dominating the market. These are especially true for materials that are needed for aerospace, under water and transportation application. Yet there is a demand for low density strong stiff abrasion and impact resistant materials which are not corroded and degraded easily.
In recent years the natural or bio fibre composites have attracted substantial importance as a potential structural material. These bio fibre composites are immersing as a viable alternative to glass fibre reinforced composite especially in automotive and building product applications. The combinations of bio-fibres such an kenaf, hemp, flax, jute, henequen, pine apple leaf fibre and sisal with polymer matrices from both renewable and non renewable resources to produce composite materials that are competitive with synthetic composites requires special attention. These composites have attained commercial attraction in automotive industries.
In the present investigation, composite samples with varying filler content (0%, 10%, 20%, 30%, 40%, 50%. 60%, 70%) are made using coir fibres as the reinforcement and polyester as the matrix. Abrasion wear studies are carried out using DUCOM FRICTION AND WEAR MONITOR. on the various coir fibre (10%,20%,30%) reinforced polyester composite have been Tests are performed varying the applied load, velocity and at abrasive particle sizes. It has been found that wear rate reduces with increase in the reinforcement content. Because, as the reinforcement content increases the material loss takes place in all directions. Also it is found that wear rate increases with increasing velocity and increasing load. The wear rate increases with bigger size of abrasive particles. Further, the examination of the worn surfaces of the composites by scanning electron microscopy(SEM) showed that the cracks were spreading in all direction at higher vol% of reinforcement (i.e 30%), also the micro grooves formed are a result of micro-ploughing.
The dielectric behavior of the coir fibre reinforced polyester composite is measured using HP-4192A LF Impedance Analyser, connected with a data acquisition system. It is found that, with increase in the amount of reinforcement, there is a decrease in the dielectric loss. With increase in the reinforcement content the dielectric constant shows a higher value than the pure polyester sample. Change in frequency shows a stabilizing trend on the dielectric constant. However with the increase in temperature the dielectric constant of the composite shows a slightly increasing trend.