中空二氧化硅微球的制备及其对聚合物复合材料导热系数的影响

doi:10.52396/JUST-2021-0072

摘要/Abstract

摘要： 中空微球/聚合物复合材料的热导系数与中空微球的含量和结构密切相关.本文以微米级单分散聚苯乙烯(PS)微球为牺牲模板,通过调控PS微球和正硅酸四乙酯(TEOS)的相对含量,制备了一系列表面包覆不同厚度SiO₂的PS@SiO₂核壳结构微球,用高温煅烧去除PS模板后,得到不同球壁内外径比(r/R)的中空SiO₂(H-SiO₂)微球.通过红外光谱、扫描和透射电子显微镜等对H-SiO₂微球的化学成分和形貌进行了表征,并进一步测定了不同含量和r/R的H-SiO₂与聚二甲基硅氧烷(PDMS)复合后得到的H-SiO₂/PDMS复合材料的导热系数,探究了H-SiO₂微球的含量和r/R对复合材料导热系数的影响.通过与中空微球/聚合物复合材料导热系数的理论模型计算结果相比较,证实了只有当H-SiO₂具有完整结构且r/R高于0.963时,其添加到PDMS中才能降低复合材料的热导系数,且下降程度随H-SiO₂含量增加而增大,从而提高复合材料的隔热性能.与此同时,当H-SiO₂添加量在质量分数5%以内时,H-SiO₂/PDMS复合材料的力学性能也随着H-SiO₂含量增加而有所增加.H-SiO₂质量分数为5%时,复合材料的拉伸强度和断裂伸长率分别提高了100%和360%.本工作为高性能中空微球填充聚合物基隔热材料的设计制备提供了理论和实验指导.

关键词: 中空二氧化硅微球, 硅橡胶, 导热系数, 隔热材料

Abstract: The thermal conductivity of polymer composites filled with hollow microspheres is closely related to the content and structure of hollow microspheres. In this paper, micron-sized monodisperse polystyrene (PS) microspheres are synthesized as the sacrificial template to prepare a series of hollow SiO₂ (H-SiO₂) microspheres with different inner and outer radius ratios (r/R).The r/R value is controlled by the relative content of PS microspheres and tetraethyl orthosilicate (TEOS). The chemical composition and morphology of H-SiO₂ microspheres are characterized by infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Further, H-SiO₂ microspheres are blended with polydimethylsiloxane (PDMS) at a certain content to obtain H-SiO₂/PDMS composite rubbers. The effect of the content and the r/R value of H-SiO₂ microspheres on the thermal conductivity of the composite rubber are investigated.Combined with the theoretical model calculation on the thermal conductivity of the silicone rubber,it can be concluded that the addition of H-SiO₂ microspheres with a complete hollow structure and an r/R value higher than 0.963 can reduce the thermal conductivity of H-SiO₂/PDMS composite rubbers.The more the H-SiO₂ microspheres, the smaller the thermal conductivity of the composite rubber.At the same time, when the mass fraction of H-SiO₂ microspheres is no more than 5%, the mechanical properties of the H-SiO₂/PDMS composite rubber are also enhanced with the increase of the weight content of H-SiO₂ microspheres. This work provides theoretical and experimental guidance for the design and preparation of high-performance hollow microspheres filled with polymer thermal insulation materials.

Key words: hollow silica microspheres, silicone rubber, thermal conductivity, thermal insulation material

中图分类号:

TB33

舒晶晶, 陈剑, 陈亚威, 赵楚, 汪谟贞, 葛学武. 中空二氧化硅微球的制备及其对聚合物复合材料导热系数的影响[J]. 中国科学技术大学学报, 2021, 51(6): 494-504.

Shu Jingjing, Chen Jian, Chen Yawei, Zhao Chu, Wang Mozhen, Ge Xuewu. Preparation of hollow silica microsphere and its effect on the thermal conductivity of polymer composites[J]. Journal of University of Science and Technology of China, 2021, 51(6): 494-504.

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