采用阴离子表面活性剂硬脂酸镁和阳离子液体1-羟乙基-3-甲基咪唑双(三氟甲烷磺酰)亚胺盐分别处理球形氧化铝,得到表面分别带阴、阳离子的改性粉体(Al2O3-ani、Al2O3-cat),X射线光电子能谱仪(XPS)和热失重(TG)分析表明制备了改性粉体。将Al2O3-cat/Al2O3-ani按质量比1∶1填充到乙烯基硅油中,制备Al2O3填充质量为88%的有机硅灌封胶基材。结果表明:Al2O3-cat/Al2O3-ani混合填充体系的黏度仅为未改性体系的33.3%。Al2O3-cat中带正电荷的阳离子与Al2O3-ani中带负电荷的阴离子因静电作用相互吸引,形成部分聚集体,聚集体外部乙烯基硅油的自由流动空间明显增加,从而有效降低了有机硅灌封胶的黏度。扫描电镜、沉降体积分析结果证实了粉末聚集体的形成。Al2O3-cat/Al2O3-ani有机硅灌封胶的黏度、导热系数分别为25Pa·s、2.80W/(m·K),为高填充量高导热有机硅灌封胶的降黏提出了一种新方法。
In this paper,spherical alumina was treated with anionic surfactant magnesium stearate and cationic liquid 1-hydroxyethyl-3-methylimidazole bis(trifluoromethanesulfonyl) imine salt to obtain modified powders (Al2O3-cat,Al2O3-ani) with anion and cation on surfaces,respectively.X-ray photoelectron spectroscopy (XPS) and thermogravimetric (TG) analysis showed that the modified powders were successfully prepared.Al2O3-cat/Al2O3-ani was filled into vinyl silicone oil with a mass ratio of 1∶1 to prepare a silicone potting adhesive base material with an Al2O3 filling content of 88wt%.The results indicated that the viscosity of Al2O3-cat/Al2O3-ani mixed filling system was only 33.3% of that of unmodified system.The positively charged cations in Al2O3-cat and the negatively charged anions in Al2O3-ani were attracted to each other by electrostatic interaction,forming partial aggregates.The free flow space of vinyl silicone oil outside the aggregates was significantly increased,thus effectively reducing the viscosity of the silicone potting adhesive.The results of SEM and sedimentation volume analysis confirmed the formation of powder aggregates.The viscosity and thermal conductivity of Al2O3-cat/Al2O3-ani silicone potting adhesive were 25Pa·s and 2.80W/(m·K),respectively,which provided a new method for viscosity reduction of high filling content and high thermal conductivity silicone potting adhesive.
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