Effect of curing time on the mechanical properties of composite coconut shell charcoal nanocarbon reinforced epoxy

Abstract Developments in composite materials have resulted in many types of compounds that utilize natural materials. One of the natural ingredients used is coconut shell. The result of processing coconut shells which are processed into charcoal can be used as reinforcement in composites. Research on composites with epoxy matrix reinforced with nanocarbon from coconut shell charcoal was given curing and non-curing treatment. Variation of curing holding time is 0.5 hours; 1.5 hours; 2.5 hours; and 3.5 hours at 80oC. Formation of nanosized carbon using a high-energy milling process with a shaker mill machine. The composite is made from a mixture of epoxy resin, hardener, and 400 ppm by weight of coconut shell charcoal nanocarbon. The ratio between resin and hardener is 2:1. The composite that has been formed is then given curing variations and its mechanical properties are observed through tensile and impact testing. The epoxy matrix composite without filler has the highest tensile strength of around 57.9 MPa at a curing time of 2.5 hours and the highest impact toughness is around 5.82 kJ/m2 at a curing time of 1.5 hours. Meanwhile, the nanocarbon-reinforced epoxy matrix composite has the highest tensile strength, which is around 59.3 MPa at a curing time of 2.5 hours and the highest impact toughness is around 9.31 kJ/m 2 at a curing time of 1.5 hours. The addition of nanocarbon particles can increase the highest tensile strength by about 23% at a curing time of 2.5 hours. However, the effect of nanocarbon on impact toughness has the highest increase of about 84.5% at a curing time of 1.5 hours. Nanoparticles and the corresponding curing time greatly affect the value of the impact toughness more significantly than the resulting tensile strength.