| 摘要 |
Ethylenically unsaturated monomer(s) are polymerized in suspension or emulsion in a closed vessel by including in the liquid medium for at least part of the process an inert substance which is more volatile than the monomer(s) and whose solubility in the monomer(s) is greater than that in the polymer being produced, and making repeated observations of the pressure or its rate of change in the vessel in order to control the process. The volatile substance may be added before, or intermittently during, the polymerization and may be propane, butane, pentane, hexane and/or cyclohexane, or mixtures such as petrol ether and ligroins, a C1- 2 halogenated hydrocarbon or diethyl ether. The monomer may be (1) a mixture of styrene, divinyl benzene and ethyl vinyl benzene; or (2) styrene and may be polymerized in an aqueous phase containing polyvinyl alcohol, polystyrene, benzoyl peroxide and petroleum ether and the polymer may be sulphonated to form a cation exchange resin; or the monomer may be (3) vinylidene chloride which may be polymerized in the presence of propane gas, and an aqueous phase containing ammonium persulphate, sodium bisulphite, sodium bicarbonate and sodium lauryl sulphonate. The polymers may be expanded by treatment with steam. |
