Effect of Hyperbranched Polyester Grafting Nanosilica on Dielectric Properties of Epoxy Resin
Yang Guoqing1, 2, Li Yang1, 2, Wang Deyi1, 2, Liu Jing2, Li Jiaxin2
1. State Key Laboratory of Eco-Hydraulics in Northwest Arid Region of China Xi’an University of Technology Xi’an 710048 China;; 2. Institute of Water Resource and Hydroelectric Engineering Xi’an University of Technology Xi’an 710048 China;
Abstract:To improve the interfacial properties of nanosilica/epoxy resin and the insulating behavior of composite materials, hyperbranched polyester and silane coupling agent were used to modify the surfaces of nanosilica in this study. Nanosilica/epoxy resin composites with different filling ratios were prepared, their dielectric properties under different modification methods were investigated. XPS and FTIR spectra show that the hyperbranched polyester can be grafted to nanosilica surface by 40 min of blending reaction under 100℃. SEM observation suggests that within 10% filling quality ratio, nanosilica particles treated by hyperbranched polyester are not prone to agglomerate in epoxy resin. TSDC measurement indicates that 0.86~1.15 eV deep traps are present in the modified nanocomposites. Moreover, the AC breakdown strength of the epoxy resin composites filled with polyester-treated nanosilica is 19% higher than that of the silane-treated composites at a filling quality ratio of 7%. The dielectric loss factor and relative permittivity of composites are also decreased to 0.58% and 4.38 at 5% filling quality ratio. The results mentioned above show that active carboxyl groups can be implanted to nanosilica surfaces by the hyperbranched polyester treatment. Terminal carboxyl radicals with long chains effectively inhibit the agglomeration of nanosilica and enhance the bonding strength between inorganic particles and epoxy matrix. As a result, trap energy of epoxy resin composites is increased, and the insulating behaviors of the epoxy resin composites are obviously improved.
杨国清,黎洋,王德意,刘菁,李嘉昕. 超支化聚酯改性纳米SiO2/环氧树脂的介电特性[J]. 电工技术学报, 2019, 34(5): 1106-1115.
Yang Guoqing, Li Yang, Wang Deyi, Liu Jing, Li Jiaxin. Effect of Hyperbranched Polyester Grafting Nanosilica on Dielectric Properties of Epoxy Resin. Transactions of China Electrotechnical Society, 2019, 34(5): 1106-1115.
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