SiO_2气凝胶/PMMA复合材料柔性相界面对导热性能的影响

Thermal conductivity of silica aerogel/PMMA composite with flexible phase interface

以正硅酸乙酯为前驱体,采用常压干燥法制备二氧化硅(SiO_2)气凝胶(SA)。通过微观形貌分析,红外光谱和热重表征SA的修饰效果;通过对复合材料导热,弯曲强度,分子量及分子量分布的测定,研究SA/聚甲基丙烯酸甲酯(PMMA)复合材料的性能。分析结果表明:SA表面的骨架颗粒分布疏松,颗粒大小均匀,具有连续网络状结构。不饱和双键能够很好的接枝到SA的表面。SA的加入使数均分子量减小,分子量分布变宽;SA含量为5%(wt,质量分数)SA/PMMA复合材料的弯曲强度达到最大值73.07MPa,导热系数为0.0589W/(m·K),具有较好的热性能,在温度为367时失重率为12%。

The preparation of SA with TEOS as silica source through sol-gel method was investigated,and the ob rained wet gelatin was dried under ambient pressure. The morphology and modification of SA were characterized by micro- scopic morphology analysis, infrared spectroscopy, thermal gravimetric analyzer. The properties of PMMA/SA composites were studied by the determination of the thermal conductivity, flexural strength,molecular weight and its distribution. The results showed that the distribution of the skeleton particles on SA surface was loose and the particle size was uniform,and had continuous network structure. The unsaturated double bond grafted onto the surface of SA. The addition of SA reduced the molecular weight, and increased the distribution index. The flexural strength of composite reached the maximum 73.07MPa,in which the content of SA was 5 %. The thermal conductivity of SA/PMMA composites was 0. 0589W/（m· K）, and the weight loss of the sample was about 12% at 367℃ ,which exhibited a well thermal stability.