Molecular dynamics simulation of the effect of the thermal and mechanical properties of addition liquid silicone rubber modified by carbon nanotubes with different radii

Abstract

Abstract For microscopic analysis of the effect of doping with carbon nanotubes (CNTs) of different radii on the thermal and mechanical properties of addition liquid silicone rubber (ALSR) composites, models of pure silicone rubber and silicone rubber composites containing CNTs of different radii were constructed based on a molecular dynamics approach using vinyl-capped polydimethylsiloxane (VPDMS) as the base polymer and polyhydroxymethylsiloxane (PHMS) as the cross-linker. The thermal and mechanical properties and microstructures of the different models were analyzed and compared. It was found that the doping of CNTs could change the thermomechanical properties of the composites, and the doping of CNTs with small radius had a more positive effect on the material, the thermal conductivity, glass transition temperature, and mechanical properties of the composites are improved. Due to the doping of CNTs, the free volume percentage and the mean square displacement of the composites are reduced. It is noteworthy that during the modeling and optimization process, there are molecular chains that pass through the large radius CNTs, and the structural properties of the composite CNTs themselves play a more critical role in the enhancement effect of the thermodynamic properties of the composites compared to the binding energy and free volume.