For insolving the problem of "oil migration" when thermal conductive silicone gel is used in aerospace environment

a polysiloxane with long branched chain is designed and synthesized (B-PDMS)

then fill nano-ZnO in it to obtain a thermal conductive silicone gel based on physical entanglement network

and fill the same amount of nano-ZnO in the linear polysiloxane with the same viscosity as comparison samples. Through the characterization of Fourier transform infrared spectroscopy (FTIR) and magnetic resonance spectroscopy (

1

HNMR)

we prove that polysiloxane with long branched chain is synthesized successfully

and we find that BPDMS has larger molecular weight and lower molecular movement ability than L-PDMS with the same viscosity. Through the characterization of environmental scanning electron microscope

thermal conductivity

rheological properties

oil migration performance and total mass loss test

it is found that nano-ZnO has better dispersion in B-PDMS; the thermal conductivity of B-PDMS based thermal conductive gel is lower than that of L-PDMS based thermal conductive gel under the same filling amount; the zero shear viscosity of B-PDMS based silicone gel is higher than that of L-PDMS based silicone gel

but the former has good thixotropy

the viscosity tends to be the same as the latter with the shear rate increasing. Importantly

the oil migration performance of B-PDMS based silicone gel has been greatly improved

the oil migration rate of thermal conductive gel filled with 200 mass parts of nano-ZnO is only 1.08

which basically realizes no oil migration; and its TML is only 0.26 wt%

which meets the requirements of the space environment for the outgassing performance of the material.