Abstract: A process which comprises producing a uniform copolymer of acrylonitrile and at least one faster-reacting aromatic olefine containing 50-95% molar of acrylonitrile units wherein the polymerization is conducted in the presence of at least one thiol as chain-transfer agent and the reaction medium is maintained at pH .ltoreq. 4.5, e.g. by using dilute sulphuric acid.

Abstract: A method is provided for the production of homogeneous copolymers from monomers having differing reaction rates; in particular copolymers of acrylonitrile or of vinylidene chloride are disclosed. The monomers are fed to the reaction mixture at a rate sufficient to maintain a constant monomer ratio in the reaction mixture throughout the course of the reaction, the rate of addition being determined by the rate of evolution of heat as measured by the rate that a cooling system removes heat evolved by the reaction. An injection-mouldable copolymer consisting essentially of acrylonitrile units and uniformly distributed units of styrene or .alpha.-methyl styrene may be produced in this way. Films of the copolymer can be oriented by stretching at 90.degree.-140.degree. C. Its softening point may be increased by copolymerizing a minor amount of N-aryl maleimide.

Abstract: Copolymers of acrylonitrile and conjugated aromatic olefines, such as styrene, containing 50-95% molar of acrylonitrile are made using an aqueous suspension process in which polyvinyl pyrrolidone is used as suspension agent.

Abstract: Copolymers of acrylonitrile and conjugated aromatic olefines, such as styrene, containing 50-95% molar of acrylonitrile are made using an aqueous suspension process in which hydroxyethyl cellulose is used as the suspension agent.

Abstract: A method of measuring the extent of an exothermic chemical reaction while the reaction is proceeding which comprises measuring the difference between the ingoing and outgoing temperatures of a coolant passing through the reaction vessel and computing therefrom the heat produced by the reaction, and in which the numerical value of the temperature of the ingoing coolant is retained in a memory device before being compared with that of the outgoing coolant, the period of retention being equal to the time taken for coolant to pass from the point of measurement of the ingoing temperature to the point of measurement of the outgoing temperature. This corrects errors due to variations with time of the temperature of the ingoing coolant.

Abstract: A method is provided for controlling polymer particle size in emulsion polymerization in which at least one emulsifier is added to a polymerization reaction mixture containing at least one ethylenically unsaturated monomer at a rate determined by the rate at which heat is evolved by free radical catalyzed polymerization of the monomer such that the total amount of emulsifier fed to the reaction mixture up to any one time is related to the total amount of heat evolved up to that time.

Abstract: A uniform copolymer containing 50 to 98% molar of acrylonitrile units or 50 to 99.5% molar of methacrylonitrile units suitable for making naturally degradable articles (wrappings, bottles) which contains as at least one copolymerized component thereof 0.1 to 25% molar of uniformly distributed units of an ethylenically unsaturated ketone of specified formula.