Abstract: In a first stage, a lactone is polymerized by an ionic route in vinyl chloride with the aid of a catalyst consisting of the product, optionally complexed with tetrahydrofuran, of the reaction of an alkylmetal with ethylenically unsaturated alcohol, optionally in the presence of water and, in a second stage, the said vinyl chloride is polymerized by a radical route in an aqueous suspension and in the presence of the polymerization medium originating from the first stage, to which other unsaturated monomers are optionally added.The invention also relates to new modified vinyl chloride polymers consisting of lactone polymers whose number-average molecular weight is less than 5,000, grafted with vinyl chloride polymers.

Abstract: The compositions contain, as vinyl chloride polymers, copolymers of vinyl chloride and of alkyl acrylates in which the alkyl radicals, consisting of linear or branched chains, contain from 1 to 10 carbon atoms and have an initial Shore A hardness not exceeding 85. They are suitable for the production of very diverse flexible articles, especially in the medical field (pouches for blood and for physiological fluids), the motor vehicle field (various profiles and seals) and the building industry (sealing sheets).