Influence of absorbed water on the dielectric properties and glass-transition temperature of silica-filled epoxy nanocomposites
Influence of absorbed water on the dielectric properties and glass-transition temperature of silica-filled epoxy nanocomposites
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吸水量对二氧化硅填充环氧纳米复合材料介电性能和玻璃化转变温度的影响
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
S. Rowe
中科院分区：
文献类型：
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作者：
C. Zou;M. Fu;J. Fothergill;S. Rowe
本文报道了纳米SiO_2填充环氧树脂在不同相对湿度和温度下的介电谱。以上的玻璃化转变温度（Tg），直流类不完善的电荷传输（QDC或LFD）占主导地位的低频介电谱。在未干燥的复合材料中发现了另一个中频弛豫过程。水还引起玻璃化转变温度降低，这可以通过介电谱和DSC测量。理论和实验都表明，纳米复合材料中可能存在比未填充的环氧树脂更高的水含量，表明纳米结构化时具有更大的自由体积。在我们的系统中，二氧化硅的亲水性表面很可能导致水包围并导致环氧树脂从SiO2中分层。这是纳米复合材料中潜在的机械和介电弱点，这可能导致老化现象。疏水性表面基团可降低纳米复合材料的吸水性。
Work on dielectric spectroscopy of epoxy resin filled with nano-SiO2 at different relative humidities and temperatures is reported. Above the glass-transition temperature (Tg), dc-like imperfect charge transport (QDC or LFD) dominates the low frequency dielectric spectrum. Another mid-frequency relaxation process was found in the non-dried composites. Water also induces glass-transition temperature decreases, which can be measured both by dielectric spectroscopy and DSC. Both theory and experiment demonstrated that a higher water content could exist in nanocomposites than unfilled epoxy suggesting a bigger free volume when nanostructured. In our system, the hydrophilic surface of silica is likely to cause water to surround and lead to delamination of the epoxy from SiO2. This is a potential mechanical and dielectric weakness in the nanocomposites, which may lead to an ageing phenomenon. Hydrophobic surface group may reduce the water adsorption in nanocomposites.