Phenolic textiles (fiber or fabric) were pyrolyzed in a nitrogen atmosphere at 500°C for up to 4 hr. One hour of pyrolysis gave optimum carbonization based on weight loss. The resulting carbon textiles were activated at 900°C in a carbon dioxide atmosphere for up to 31/2 hr. The level of activity attained was determined routinely by carbon tetrachloride vapor sorption. Surface area, pore diameter, and pore volume determinations were conducted on representative samples. Surface areas as high as about 2800 m 2 /g were attained.
A commercial carbon fabric intended for aerospace applications was characterized as an activated carbon, since it had sufficient surface area and pore volume to warrant such consideration. Evaluation was achieved by means of nitrogen sorption (BET method), mercury porosimetry, sorption of CCl4 vapor, density in water and helium, and sorption of Meth ylene Blue from aqueous solution. The carbon textile appeared to be most suitable for gas and vapor sorption, but a signifi cant capacity for liquid phase sorption was also demonstrated.
Abstract-A critical review of photochromism in triphenylmethane derivatives and some related compounds is presented. Most of the triphenylmethane compounds reported to be photochromic as well as some of those reported as non-photochromic are mentioned. Compounds were included only if the conditions under which the observations were made were reasonably well described. Qualitative observations of photochromism are predominant since very little quantitative data are available. Physical properties of the compounds and/or their solutions which appear to be related to photochromism are discussed including conductivity, dielectric constant and dipole moment. Among other topics discussed are mechanisms and kinetic studies.
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