Abstract
The doping of nano-SiO2 filler is one of the main methods of improving the thermomechanical properties of epoxy resin (EP) composite insulating materials, and the characteristics of the filler is one of the important factors affecting the modification effect. In this paper, the effects of the shape and mass fraction of nano-SiO2 particles on the microstructure and thermomechanical properties of EP composites were studied by molecular dynamics simulation. The results show that the bonding energy (EBinding) between the spherical SiO2 filler and matrix is the largest, and the fraction free volume (FFV) and the mean square displacement (MSD) of the composite model are the lowest. With the increase of the filler mass fraction, the EBinding between the filler and matrix changed little, whereas both FFV and MSD showed a monotonous downward trend. The introduction of nano-SiO2 fillers can significantly improve the thermomechanical properties of the composites. The shape of the filler has little effect on the glass transition temperature (Tg), coefficient of thermal expansion (CTE), and mechanical properties of the composites. Increasing the mass fraction of the filler can obviously improve the modification effect. When the mass fraction of SiO2 is 15 wt. %, the Tg of the material increased by about 35 K, the glass state CTE decreased by about 35%, and the Young’s modulus and shear modulus increased by 24.56% and 32.45%, respectively.
Highlights
The crosslinking product of epoxy resin (EP) and curing agent is a thermosetting material with three-dimensional crosslinking network
The results show that the bonding energy (EBinding) between the spherical SiO2 filler and matrix is the largest, and the fraction free volume (FFV) and the mean square displacement (MSD) of the composite model are the lowest
When the mass fraction of SiO2 is 15 wt. %, the Tg of the material increased by about 35 K, the glass state coefficient of thermal expansion (CTE) decreased by about 35%, and the Young’s modulus and shear modulus increased by 24.56% and 32.45%, respectively
Summary
The crosslinking product of epoxy resin (EP) and curing agent is a thermosetting material with three-dimensional crosslinking network. Different preparation methods lead to different shapes of nano-SiO2.15,16 the study of the effects of the filling amount, particle size, and shape of nano-SiO2 fillers on the thermomechanical properties of EP composites is of great significance in the development of EP composites. Zhang et al investigated the effect of modified SiO2 on the thermomechanical properties of an amine curing agent/DGEBA composite by MD simulation combined with experiment.. We focused on the effects of mass fraction, particle size, and shape of nano-SiO2 fillers on the microstructures and thermomechanical properties of EP nanocomposites. The effects of the filler shape and mass fraction on the thermomechanical properties of epoxy nanocomposites (EP/Nano-SiO2) were investigated, and the effect mechanism of micro-structure of EP/Nano-SiO2 composites on the thermomechanical properties of materials was analyzed. In order to calculate the thermomechanical properties and analyze the structure–property relationships of the EP/nano-SiO2 composites, the crosslinked models of the EP and EP composite were calculated using the Materials Studio (MS) 7.0
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