Abstract: In apparatus for polymerizing high-pressure ethylene to produce polyethylene, a tubular reactor is connected to a source of high pressure ethylene. An intensifier supplies an initiator solution to the tubular reactor. This solution includes one or more catalysts which promote the polymerization reaction. Within the tubular reactor, a peak temperature occurs in proximity of the point at which the catalysts are introduced. If the catalysts are introduced at more than one point, peak temperatures will result downstream of each of such points. For various reasons, the peak temperatures are displaced along the tubular reactor and a plurality of thermocouples are distributed at spaced positions in the tubular reactor to measure the temperatures at the positions at which the peak temperature might occur.

Abstract: A control method wherein the control signal is generated from a disturbance signal, the functional relationship between these signals being an equation based on two dead times and a first order lag and a first order lead, the ratio of the time constants of this equation being equal to the fourth power of the ratio of the time constants of the disturbance dynamics and of the control dynamics of the process to be controlled.

Abstract: Homopolymers and copolymers of vinyl chloride are produced in the form of a powder by a bulk polymerization process which involves a dual temperature operation. Vinyl chloride (either alone or admixed with other copolymerizable monomers) is contacted with conventional polymerization initiators in the absence of solvents or diluents at a first temperature of from about 68.degree. to about 110.degree. F until the polymerization has proceeded to 0.1 to 10% of completion and thereafter the temperature is raised to 120.degree. to 150.degree. F until the polymerization has reached the desired conversion.

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: 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: The catalyst stream used for regulating high pressure polymerization reactions of monoolefins such as ethylene can be supplied in a positive, clean and accurately controllable fashion by delivering it through a separate conduit which terminates in an orifice tip located within and substantially coplanar with the entry port of the monomer stream into the reaction zone. The subject technique simplifies start-up as well as maintenance of good temperature control throughout the polymerization process.

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.