Preparation of Thermal Conductivity Silicone Gel with Low Permeability and High Filling
Thermal conductivity silicone gel with low permeability and high filling was prepared by 200 mPa·s(PDMS-Vi200)and 500 mPa·s(PDMS-Vi500)as silicone oil,0.05 wt％hydrogen silicone oil(PDMS-H)as cross-linking agent,and 5 μm(AO-05),20 μm(AO-20)and 40 μm(AO-40)spherical Al2O3 added with different ratios as heat conduc-tion filler.The effects of spherical Al2O3 and viscosity of PDMS-Vi on viscosity of adhesive and the maximum filling were stud-ied.The effects of γ-mercaptotrimethoxysilane(KH590)on the thermal conductivity of silicone gel,as well as viscosity of PDMS-Vi,ratios of Si—H to Si—Vi and filling amount on the hardness,density,thermal conductivity and mechanical strength of silicone gel.The influence of the type and proportion of aluminua complex ligand on the anti oil permeability and heat resistance of silicone gel was studied.The results show that the thermal conductive silicone gel has been prepared by vinyl-terminated sili-cone oil,0.05 wt％hydrogen silicone oil as the crosslinking agent,and spherical Al2O3with different particle sizes as filler.U-sing silicone oil with different viscosity as the base oil,0.05 wt％hydrogen silicone oil as the crosslinking agent,and spherical Al2O3 with different particle sizes as the composite thermal conductive filler,thermal conductive silicone gel with low permeabili-ty and high filling has been prepared.When using 20 μm spherical Al2O3 with a uniform particle size,there is no obvious in-crease on viscosity of the gel and the maximum filling is up to 1500 phr.The appropriate amount of KH590(2.00 wt％)effec-tively improves the thermal conductivity of the silicone gel.When PDMS-Vi200 is used as silicone oil,the ratio of Si-H to Si-Vi is 0.8∶1,AO-20 is used as thermal conductivity filler(600 phr),silicone gel has better performance,with Shore OO hardness of 67,density of 1.83 g/cm3,thermal conductivity of 3.69 W/(m·K)and tensile strength of 1.95 MPa.The thermal conductivity of thermal conductive silicone gel prepared with different particle sizes is higher than that with one particle size,and when the mass ratio of AO-20 to AO-05 is 2/1,the silicone gel has a better thermal conductivity of 4.7233 W/(m·K).Due to the surface silanization of spherical Al2O3,winding of silicone oil and hydrogen bonding effects of sulfhydryl groups with residual double bonds,it can significantly improve the permeability and heat resistance of silicone gel.Moreover,the silicone gel prepared by AO-20 to AO-05(mass ratio of 2/1)has better anti oil permeability and heat resistance,the oil permeability ratio is 1.0476,5 wt％weight loss temperature of 331 ℃ and the residual mass fraction of 89.10％at 700 ℃.
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