HNTs/SiO2复合气凝胶制备及其性能研究

采用正硅酸乙酯(TEOS)为硅原,以硅烷改性的埃洛石纳米管(HNTs)为增强相,利用CO2超临界干燥技术制备具有优良力学和隔热性能的HNTs/SiO2复合气凝胶.利用傅立叶红外光谱、扫描电镜、比表面积与孔径分析仪、万能试验机和导热率测量仪等手段对HNTs改性后的表面状态、HNTs/SiO2复合气凝胶的微观形貌、孔结构、力学和导热性能进行了测试分析.结果表明:改性后的HNTs均匀分散到二氧化硅气凝胶基体中,并与SiO2纳米颗粒实现良好的结合,HNTs/SiO2复合气凝胶呈三维网络结构,当HNTs含量为15wt;时,平均孔径为10.47 nm;随着HNTs含量的增加,复合气凝胶的力学性能不断增强,同时其导热系数也不断增大,当HNTs含量为15wt;时,HNTs/SiO2复合气凝胶的抗压强度为0.85 MPa,导热系数为0.024 W/mK.

Preparation and Properties of HNTs/SiO2 Composite Aerogels

HNTs/SiO2 composite aerogels with excellent mechanical properties and thermal insulation performance were prepared via supercritical CO2 drying,employing tetraethoxysilane (TEOS) as silicon source and halloysite nanotubes (HNTs) modified by isooctyltriethoxy silane as reinforcing phase.Surface states of HNTs after modification,the morphology,pore structure,mechanical properties,and thermal conductivity of composite aerogels were investigated by FTIR,SEM,surface area and porosity analyzer,universal testing machine and thermal conductivity measurement.Our results reveal that the modified HNTs are uniformly dispersed into the silica gel matrix,and make good combinations with SiO2 nanoparticles.HNTs/SiO2 composite aerogels exhibit a three-dimensional network structure,when the content of HNTs is 15wt;,the average pore size of aerogels is 10.47 nm;with the increase of HNTs content,the mechanical properties of composite aerogels are improved,and the thermal conductivity also increase continuously.When the HNTs content is 15wt;,the compressive strength of HNTs/SiO2 composite aerogel is 0.85 MPa,and the thermal conductivity is 0.024 W/mK.