Properties of Reinforced Polymer Composite Produced from Coconut Fiber

This study aimed at the production of reinforced polymer composites from coconut fibers and plastics. Coir Fiber (CF) sheets with dimensions of 200 x 200 x 12 mm (+ 3mm) were used as the natural fiber, whereas a thermosetting plastic or an elastomer (unsaturated polyester [UPE] or silicon rubber [SIR]) was used as the binder in the matrix. Processing was performed using the vacuum infiltration method, wherein the liquid polymer was made to infiltrate the cellulose of the natural structure of the CFs and disperse within the CF matrix. The effect of production variables on thermal, sound, and flexural properties was evaluated. Material characterization tests revealed that the addition of the UPE and SIR as reinforcing materials enhanced the thermal conductivity of the CFs. UPE improved the modulus of rupture of the CFs. The study further revealed that CF/SIR composites showed high ductility. Analysis of the sound absorption properties of the composites revealed that the noise reduction coefficient (NRC) of the CF/400 wt% SIR composite was the highest. Moreover, the CF/SIR composites showed higher sound absorption efficiency (α) values at high frequencies than those of the CF/UPE composites. However, the polymers had no effect on the NRC of the neat CFs when added in a low concentration (200 wt%). This study shows that coconut husk waste can be used to produce reinforced polymer composites with desirable thermal conductivity and sound absorption characteristics.