Wang Lukai, Feng Junzong, Jiang Yonggang, Li Liangjun, Feng Jian
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology 109 De Ya Rd Changsha Hunan 410073 People's Republic of China
RSC Adv. 2019 Mar 8;9(14):7833-7841. doi: 10.1039/c8ra10493j. eCollection 2019 Mar 6.
The traditional SiO aerogels are difficult to apply in the fields of energy storage and heat insulation due to their poor mechanical properties. In order to deal with this issue, the polyvinylpolymethylsiloxane aerogel (PVPMSA) materials with fine mechanical flexibility and excellent thermal insulation properties are suitable substitutions. In this paper, the double cross-linking organic-inorganic hybrid PVPMSAs were prepared through the processes of free radical polymerization and hydrolytic polycondensation. The internal silica network reinforced with aliphatic hydrocarbons has significantly improved the mechanical properties and acquired a high specific surface area, reaching up to 1218 m g. Furthermore, the thermal conductivity of monolithic PVPMSAs has been investigated by changing the density and environmental conditions. Results show that PVPMSAs at 25 °C in 5 Pa have a thermal conductivity as low as 14.69 mW m K, and the solid thermal conductivity shows a flat growth with the increase of density. Meanwhile, the nanosize pores could significantly inhibit the heat transfer of gas. As for the radiative thermal conductivity, it is greatly affected by temperature. All these results obtained from this paper would help us to design thermal insulators reasonably.
传统的二氧化硅气凝胶由于其较差的机械性能而难以应用于能量存储和隔热领域。为了解决这个问题，具有良好机械柔韧性和优异隔热性能的聚乙烯基聚甲基硅氧烷气凝胶（PVPMSA）材料是合适的替代物。本文通过自由基聚合和水解缩聚过程制备了双交联有机-无机杂化PVPMSA。用脂肪烃增强的内部二氧化硅网络显著改善了机械性能并获得了高达1218 m²/g的高比表面积。此外，通过改变密度和环境条件研究了整体式PVPMSA的热导率。结果表明，在5 Pa、25°C条件下的PVPMSA的热导率低至14.69 mW/(m·K)，并且固体热导率随密度的增加呈平稳增长。同时，纳米尺寸的孔隙可显著抑制气体的热传递。至于辐射热导率，它受温度的影响很大。本文获得的所有这些结果将有助于我们合理设计隔热材料。
