氧化铝的表面改性及其在导热有机硅灌封胶中的应用

比较了3种硅烷偶联剂对氧化铝的表面改性效果。相对于未改性氧化铝,十六烷基三甲氧基硅烷、γ-氨丙基三乙氧基硅烷和乙烯基三(β-甲氧基乙氧基)硅烷改性氧化铝的吸油值分别降低了56.8%、32.5%、35%,而对应的硅橡胶胶料的黏度分别降低了74.3%、48.6%和45.4%,分散性提高,颗粒无明显团聚,改性效果突出;十六烷基三甲氧基硅烷的改性效果最优,其最佳用量为氧化铝粉体质量的1.5%。将十六烷基三甲氧基硅烷改性氧化铝填充至有机硅灌封胶中,考察了填充量对硅橡胶导热性能、黏度和力学性能的影响。结果表明,当改性氧化铝的填充量为900份时(相对于100份乙烯基硅油),胶料的黏度仅11 800 mPa.s,硫化硅橡胶的热导率高达2.47 W/m.K,拉伸强度1.6 MPa,拉断伸长率35%。

Surface Modification of Alumina and its Application in Thermal Conductivity Silicone Potting

A long chain silane coupling agent hexadecyl trimethoxysilane was used to modify surface of alumina particles and the oil-absorbed value of the modified alumina and viscosity of the corresponding silicone potting was reduced 56.8%,32.5%,35% and 74.3%,48.6%,45.4% respectively,compared with the unmodified alumina and modified alumina by γ-aminopropyl triethoxysilane and vinyl-tris(β-methoxyethoxy)silane.Meanwhile,the dispersion of the modified alumina was improved with no obvious particle agglomeration,and the effect of alumina modification was prominent with the best loading of the long chain silane coupling agent of at 1.5 wt% of alumina.The modified alumina was added to addition-type silicone and the effect of the loadings of the modified alumina on the thermal conductivity,viscosity,and mechanical properties of silicone were investigated.The results showed that with the alumina loading of 900 phr(relative to 100 phr silicone) the resulting modified silicone had a viscosity of 11 800 mPa · s a thermal conductivity of up to 2.47 W/(m · K) after cure a tensile strength of 1.6 MPa,and a elongation at break of 35%.