In order to analyze the effect of SiO

2

filling and surface modification on the epoxy resin on the micro level

silica/epoxy resin composite models were built by molecular dynamics method

and the effects of SiO

2

surface grafted with silane coupling agent KH550 on the structure

thermal properties and mechanical properties of the composites at different temperatures were investigated. The studies show that the glass transition temperature

thermal conductivity and mechanical properties of epoxy resin were improved by the addition of SiO

2

the coefficient of thermal expansion of epoxy resin SiO

2

was reduced

and the thermodynamic properties of

epoxy resin was further improved by grafting silane coupling agent on the surface of SiO

2

. It is also found that the increasing amplitude of glass transition temperature of the model of SiO

2

grafted ratio 5% and 10% rise from 15 K to 27 K and 36 K respectively

compared to the model of silica unmodified. The increasing amplitude of thermal conductivity at room temperature rise from 33.04% to 60.02% and 67.07% respectively

compared to the model of silica unmodified. With the rise of temperature

the thermal conductivity of the four models increase linearly in the range of 250

4

50 K. The elastic modulus and shear modulus of the four models decrease with the rise of temperature

and even decrease rapidly when the temperature is higher than glass transition temperature

but show a small decline when the temperature reaches over 500 K.