Improving Inherent Thermal Conductivity of Epoxy Resins Based on Contribution Components of Thermal Conductivity: A Molecular Dynamics Study

The inherent thermal transport properties of epoxy resin are vital factors to be studied in applications. In the present work, we constructed the amorphous crosslinking structure, the step crosslinking structure and the ordered crosslinking structure based on molecular dynamics theory, and used the reverse nonequilibrium molecular dynamics (RNEMD) method to calculate the thermal conductivity (TC) of different structures. Based on the numerical verification of the reliability of the method, the contribution of bonding to the TC was enhanced by increasing the molecular arrangement orderliness to reduce phonon scattering, taking the composition of the TC contribution as the guide. Meanwhile, the contribution of non-bonding interaction to the TC was enhanced by using compression process to achieve TC increase in the epoxy resin intrinsic structure, followed by exploring the effect of cross-linking degree on the TC of different structures. The results showed that the TC of amorphous epoxy resin decreased with the increase of crosslinking degree, and the relative high-frequency VDOS increased, but the influence of crosslinking degree on TC was minor in the range. For amorphous epoxy resin four-sided pressurization varied in the range of 0-7 Gpa, the non-bond energy percentage increased in the range of 0-60%, and the increase of non-bond energy made its contribution to TC increased significantly. The epoxy resin achieved 215% improvement in intrinsic TC by changing the molecular arrangement orderliness. The ordered structure TC varied from 0.3 to 3.5 W/(m & sdot;K) in the pressure variation range of 0-7 GPa. As the structure becomes more ordered, the TC increased significantly with the degree of cross-linking. The study provided the theoretical basis for the realization of resin preparation and resin thermal property evaluation with regulated intrinsic TC.