Mechanical Properties of Coir Fiber Reinforced Epoxy Resin Composites for Helmet Shell.

Abstract

Various filler loadings (10,20,30,40 & 50 weight%) of coir fiber/ epoxy resin composites have been formulated for possible helmet shell fabrication. The fiber length was 30mm and the ratio of epoxy resin: hardener was 1:0.8. A total of 50 numbers of short beams of 4 mm х 19 mm х 300 mm were produced and tested in flexure using universal testing machine. Impact test and tensile test were also carried out. The impact strength, tensile strength and tensile modulus were then calculated. It was observed that the tensile strength of coir fiber/epoxy resin composites was maximum at 30 wt% filler loading (23.68 N/mm²). The charpy notch impact strength was also maximum at 30 wt.% (26.43KJ/m²). The value however began to decrease as the filler loading increased. Currently, industrial helmet shell is fabricated from Polycarbonate (PC) and Acrylonitrile butadiene styrene (ABS). Their tensile strengths are PC; 60 N/mm² and ABS; 46 N/mm² while their charpy notch impact strengths are PC; 20.00-30.00 KJ/m² and ABS; 10.00-29.00 KJ/m². The values of coir/ epoxy resin composites fabricated are close to those of PC and ABS. Again, the tensile modulus of coir/epoxy resin composites was found to increase with an increase in filler loadings as follows: 10 wt.%. (900.00N/mm²), 20 wt.% (977.80N/mm²), 30 wt.% (1000.00N/mm²), 40 wt.% (1066.67 N/mm²) and 50 wt.% (1733.3 N/mm²). On the other hand, tensile modulus for ABS is 1,910 MPa. Hence, coir/epoxy resin composite was used in industrial helmet fabrication using hand lay- up technique to save cost.

Keywords: coir fiber, helmet shell, mechanical properties.