β Scribed by D. Gondy; P. Ehrburger
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Isotropic pitch-based carbon fibres are activated by carbon dioxide and by steam at a temperature ranging from 850 to IOOO'C. In both cases, a significant increase in micropore volume, as measured by physical adsorption of N, and COZ. is found. Fibre diameter steadily decreases during gasification by steam. In contrast, an intermediate diameter increase is observed during activation by CO,. The interval of burn-off corresponding to fibre swelling depends on the gasification temperature. Phenolic resin-based fibres do not show swelling which indicates that it is specific to pitch-based fibres activated by CO,. Oxygen is taken up during swelling on the incompletely stabilized part of the isotropic pitch-based carbon fibres. The origin of swelling and its effect on microporosity are discussed in relationship to fibre stabilization during activation.
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Study on concrete with low-
Fine holes have been laser-drilled in bundles of carbon fibres, using a pulsed Nd:YAG laser (l ΒΌ 1:06 mm). Examination of the drilled fibres showed that some were significantly swollen, with diameter increases up to $60%. Scanning electron microscopy (SEM) and Raman spectroscopy have been used to in
Wood tar pitches are generated as by-products by the charcoal manufacturing industry. They have a macromolecular structure constituted mainly by phenolic, guaiacylic, and siringylic units common to lignin. Due to their characteristics, biopitches are been investigated as precursors of carbon materia