Evaluation of surface roughness of fibrous minerals by comparison of BET surface area and calculated one

Abstract

The Japan Fibrous Mineral Research Association (JFMRA) provides standard fibrous materials consisting of man-made mineral fibres (MMMFs), whiskers and a natural mineral fibre. In this research, the BET surface areas (SABET) of JFM standard samples as well as some other natural mineral fibres were measured by krypton gas adsorption. Calculated surface areas (SAcal) were calculated from the measured length and width of individual fibres. Obtaining the ratio of SABET–SAcal for each sample, we examined its applicability to the evaluation of surface roughness of fibre, because the large ratio could be obtained for rough surface fibres. The ratios of MMMFs were about 1.0 reflecting their smooth surfaces. Meanwhile the ratios of some whiskers and natural mineral fibres were in the range of 1.3–2.4 implying rough surfaces. Our earlier observations of the fibre surfaces by electron microscopy support that some fibres with rough surfaces have a large value of the ratio. The ratio of SABET–SAcal is a method of quantitative measurement to evaluate surface roughness of mineral fibres, which will be used as a parameter to assess their biological effects.