Abstract: Vinyl polymers, e.g., the homo- and copolyvinyl chlorides, are prepared in one or more stages, to a degree of conversion of at least 50%, by suspended emulsion polymerizing at least one vinyl monomer, e.g., vinyl chloride, said at least one monomer having dispersed therein finely divided droplets of an aqueous solution of at least one component of a polymerization initiating system, and wherein the amount of water in said aqueous solution constitutes at least 19%, and preferably at least 20% by weight of the at least one monomer.

Abstract: Vinyl polymers, e.g., the homo- and copolyvinyl chlorides, are prepared in one or more stages, to a degree of conversion of at least 50%, by suspended emulsion polymerizing at least one vinyl monomer, e.g., vinyl chloride, said at least one monomer having dispersed therein finely divided droplets of an aqueous solution of at least one component of a polymerization initiating system, and wherein the amount of water in said aqueous solution constitutes at least 19%, and preferably at least 20% by weight of the at least one monomer.

Abstract: A process for degassing polymers and copolymers which are prepared by bulk polymerization of a vinyl chloride-base monomer composition, in which the polymerizate is kept in an agitated condition, the monomer composition to be removed is adjusted from the polymerization pressure to an absolute pressure of less than 0.16 bar, the polymerisate is brought to or maintained at a temperature which is at least equal to 70.degree. C. and lower than the temperature at which degradation of the polymer or copolymer begins, and said pressure and temperature conditions are maintained substantially until degassing stops. After the proportion of residual vinyl chloride monomer in the polymer or copolymer has been reduced to a value below 2000 mg/kg, the polymerizate is brought into contact with water to which at least one anionic surface active agent is added.

Abstract: Vinyl chloride polymers are prepared by polymerization or copolymerization in mass, in two phases, comprising prepolymerizing vinyl chloride monomers in a first phase under highly turbulent agitation until a degree of conversion thereof between about 5 and 15% is attained, and thence, in a second distinct phase, polymerizing said prepolymerized reaction product through reaction completion under mild agitation, said process being characterized in that [1] there is added to the reaction medium, prior to same attaining a polymer content of about 15% by weight, an additive selected from the group comprising (a) a copolymer of vinyl acetate and an ethylenically unsaturated carboxylic acid monomer copolymerizable therewith, and (b) a condensate of ethylene oxide on a polypropylene glycol backbone, and in that [2] the reaction rate is controlled such that the period of time during which the content by weight of polymer or copolymer in the reaction medium is comprised between 15 and 25% is less than 45 minutes.