Documents x-ray diffractometry 2 results

The mineral phases and chemical and physical characteristics of the chrysotile-A (12001295), chrysotile-B, crocidolite (12001284), amosite (12172735), and anthophyllite (17068789) samples prepared by the International Union Against Cancer (UICC) in 1966 were examined in this study. Mineral phases were determined through the use of X-ray diffraction (XRD). Anthophyllite, talc (14807966), and nonfibrous minerals were detected in samples of chrysotile-A. The quantity of anthophyllite in chrysotile-A was estimated at 2%. The proportions of chrysotile in chrysotile-A and chrysotile-B were 94% and 92%, respectively. Amosite and crocidolite samples each contained about 1% quartz (14808607). The anthophyllite sample contained about 5% each of chlorite and mica, and about 20 to 30% talc. Overall, the chemical compositions of the samples indicated high purity. Chrysotile-B contained higher concentrations of some constituents than chrysotile-A, while anthophyllite contained high concentrations of oxides, indicating an impurity. Thermal analysis of the chrysotiles and anthophyllite indicated dehydroxidation and recrystallization. No mineral impurities were detected in the amosite and crocidolite samples by thermal analysis. Analytical transmission electron microscopy revealed that the chrysotiles consisted of thin, curly fibrils, fiber bundles, and platy materials, while amosite, crocidolite, and anthophyllite consisted of wider, rectangular fibers. The mean lengths of the chrysotile and crocidolite fibers were shorter and exhibited less variability than those of the amosite and anthophyllite samples. The mean fiber widths of the chrysotiles were less than those of amosite, crocidolite, and anthophyllite. The authors conclude that further study is necessary, since the characteristics of the UICC asbestos samples measured with modern equipment and techniques differ from those that were established years ago.

"BACKGROUND Among asbestos substitute fibres, man-made organic fibres (MMOFs) are currently being put to interesting uses in industrial applications. These fibres are classified by the International Agency for Research on Cancer (IARC) as Group 3: unclassifiable as to carcinogenicity in humans.OBJECTIVES The objective of this study is to provide a comprehensive review of the toxicity of some MMOFs currently used as asbestos substitute material and to prepare an analytical reference catalogue that would allow to identify these fibres in commercially available materials.METHODS The diameters of 100 fibres each of polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyethylene (PE) and aramids were measured by scanning electron microscopy. Each material was analyzed by diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) and X-ray diffractometry (XRD).RESULTSThe four materials examined for the purposes of this study were found to be non-respirable due to their geometric characteristics, since their average diameters were calculated at 10.5 ?Ìm for PAN, 14.20 ?Ìm for PVA, 20.5 ?Ìm for PE and 11.7 ?Ìm for aramid fibres. Only aramid fibres, which may produce fibrils of respirable size when subjected to abrasion or other types of stress, were found to have fibrils with a diameter of less than 1 ?Ìm. For this reason, high priority was given by the IARC and the World Health Organisation (WHO) to re-evaluate the hazards of these fibres. In conclusion, DRIFT spectra and the diffractograms of the four materials examined here are presented and discussed."