| 摘要 |
<p>Bulk or gas phase polymerisation of vinyl monomers is carried out with the catalyst in an aqueous solution whose water content is sufficiently low that the polymer can absorb it and maintain a consistency ranging from a dry powder to a wet cake. The catalytic element comprises a support which has been impregnated with the catalyst solution, and the weight ratio water: support is between 0.02:1 and 1.5:1, particularly between 0.05:1 and 1.1:1. Pref. monomers are vinyl chloride, styrene, acrylonitrile and alkyl (meth) acrylates. Typical catalysts are alkali or ammonium persulphates or perborates and typical supports are silica, glass fibres or CaCO3. Unlike solution or emulsion polymerisations, the polymer is obtained as a powder and without the inclusion of emulsifiers etc.</p> |
