Browsing by Author "Ball, Matthew C."

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    Studies in the system calcium sulphate/water. Part 5.—Surface area and porosity changes in the dehydration of calcium sulphate dihydrate
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (06), 1977) Ball, Matthew C.; Norwood, Leslie S.
    Changes in surface area and porosity caused by heating calcium sulphate dihydrate have been studied by nitrogen sorption at 77 K, with limited oxygen and argon studies at the same temperature. Hysteresis is observed, mainly in hexagonal CaSO4, but the observed increases in surface area are not accompanied by marked increases in porosity. Sintering, with a consequent reduction in surface area is only observed in orthorhombic CaSO4. The oxygen and argon sorption results are interpreted in the light of previous work.
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    Studies in the system CaSO4+ H2O. Part 6.—Surface chemistry and porosity of the CaSO4 hemihydrates
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (06), 1978) Ball, Matthew C.; Norwood, Leslie S.
    Measurements of surface area and pore size distributions have been used to compare the two forms of calcium sulphate hemihydrate. The α-form, prepared from solution has a low surface area and transitional pores. Dehydration causes a reduction in the volume of the smaller transitional pores and subsequent rehydration causes little change. The β-form has a higher surface area and larger pores. Dehydration increases the volume of the smaller transitional pores and again the effect of rehydration is negligible.