纳米纤维状白炭黑的孔隙特征

Porous properties of nano-fibriform silica from natural chrysotile

在与传统白炭黑对比研究基础上,利用TEM、XRD、FT_IR和氮吸附法对纳米纤维状白炭黑(MLD为92.73%)进行研究,主要讨论了纳米纤维状白炭黑多孔结构的成因、孔径大小、孔分布及孔类型等特征。分析表明纤蛇纹石中氢氧镁石八面体层被酸溶蚀和硅氧四面体层的塌陷是导致这种白炭黑具有多孔纳米纤维结构的直接原因;有两种孔隙类型,即纤维上的孔隙和纤维的堆积孔隙;纤维上的孔隙包括SiO_2微粒间的孔隙、其聚结体间的孔隙、残余纳米管的管道和毛细管道;孔径2.1和3.8nm处的孔隙数量多,并且在纳米纤维(或管)上存在大量小于5nm左右的微孔。研究证明了在用于橡胶、塑料填充补强剂和催化剂载体等方面,纳米纤维状白炭黑更优于传统白炭黑。

With TEM, XRD, FT-IR, and the physical gas adsorption techniques, porous properties of nano-fibriform silica （MLD： 92.73 % ） from natural chrysotile were studied. The results indicate that nano-fibriform silica is porous and that the nano-fibriform structure is attributed to the complete dissolution of the brucite octahedral sheets of chrysotile and the collapse of some Si-O tetrahedral sheets. Its length is at the micron or nanometer scale. There are two types of pores： cumulate pores and pores on the nanofibre. The latter pores, whose apertures are less than 5 nm, consist of pores among the particulate SiO2, pores among the aggregates of particulate SiO2, remnant nano-tunnels and capillaries. These pores belong to mesopores whose apertures are mainly of 2.1 and 3.8 nm. As the carrier of catalyzer and the filler to reinforce rubber and plastics, nano-fibriform silica shows better performance than traditional silica.