Molecular Dynamics Simulation of the Influence of Functionalized Doping on Thermodynamic Properties of Cross-Linked Epoxy/Carbon Nanotube Composites

To explore the effect of carbon nanotube functional doping on the thermodynamic properties of epoxy resin/carbon nanotube nanocomposites, based on the molecular dynamics simulation method, epoxy resin (EP) group nanocomposites doped with functionalized carbon nanotube (CNT) were designed, i.e., pure epoxy resin (EP/neat) model and 7 doped EP/neat models. The doped EP/neat models include doped un-functionalized, amino amine functionalized, carboxyl functionalized, and hydroxyl functionalized CNT models, wherein the functionalized CNTs are grafted four or eight functional groups. Accordingly, the thermal diffusion coefficient (thermal conductivity and specific heat capacity), glass conversion temperature and mechanical properties were calculated under LAMMPS. The results show that the physical properties of epoxy resin nanocomposites doped with carbon nanotubes are improved to different degrees, and the properties of EP/CNTs doped with eight functional groups are better than those of EP/CNTs doped with four corresponding functional groups. EP/AFCNT8 has the most obvious improvement in thermal conductivity, thermal diffusion coefficient and mechanical properties. The overall thermal conductivity and thermal diffusion coefficient increase by 54.92% and 67.30%, respectively. EP/HFCNT8 has the highest glass conversion temperature with an increase of 69.47K, and EP/AFCNT8, which is only inferior to EP/HFCNT8, has a conversion temperature of 58.97K. EP/CFCNT8 has the most significant increase in bulk modulus and Young's modulus at 400K, which are 52.4% and 35.5%, respectively. Due to the cross-linking reaction between amino group and epoxy matrix, the increase in the modulus of EP/AFCNT8 is more obvious, which can better maintain good mechanical properties. © 2021, Electrical Technology Press Co. Ltd. All right reserved.