Mechanical properties of graphene- and carbon nanotube-reinforced Araldite LY 5052/Aradur HY 5052 epoxy resins were investigated by molecular dynamics simulations. The COMPASS II force field was implemented in the simulations. Mechanical properties of the reinforced araldite/aradur resin epoxy system with CNT reveal the highest Young's, bulk, and shear modulus alongside the lowest Poisson ratio for 4.5% wt CNT; as Young's modulus was enhanced from 3.36 to 4.92 GPa. For values higher than 4.5% CNT, improving trend of properties ceases. This is due to the fact that in higher percentages of CNTs, agglomeration happens, which leads to the lower strength of the system. The results also indicated that by increasing weight percentage of CNT, the glass transition temperature of the system increases. Moreover, for higher diameters of CNT, not only have mechanical properties been improved but the glass transition temperature has also been enhanced. The results of the graphene-reinforced resin epoxy system imply that optimum desirable properties are acquired in lower concentrations of graphene. As in higher densities, the tendency of graphene sheets to form van der Waals bonds leads to the agglomeration in the system, worsening the properties. The sample with 8.8% graphene holds the highest values of Young's and shear modulus, whereas the highest bulk modulus and lowest density is for the sample with 4.6% graphene. Glass transition temperatures of the samples increased by adding graphene overall. However, samples with more than 8.8% did not follow the same rising trend.
Keywords: Araldite LY 5052/Aradur HY 5052 epoxy resins; Carbon nanotube and graphene reinforcement; Mechanical properties; Molecular dynamics simulation.