| 摘要 |
Polymers of methacrylic acid, partly esterified with mono-alkyl-polyalkylene glycol, are used as dispersants for aqueous compositions of calcium sulfate hemihydrate. These dispersants make it possible to control the time of onset and/or end of setting. The use of a dispersant (I) for aqueous compositions of calcium sulfate hemihydrate (II) makes it possible to control the time of onset and/or completion of setting. This dispersant (I) comprises at least 75% (by number) of random linear chains made up of units of formula (I) and (II), with units of type (II) making up 5-60% of the total (I + II) and with oxypropylene groups being distributed randomly (or not) between the oxyethylene groups. X = H, alkali or alkaline earth metal, or ammonium n = 1-250 m = 0-100 with m being less than n R = 1-12C alkyl An Independent claim is also included for aqueous compositions of (II) containing (I).
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