Abstract: A method is described for immediately terminating free radical polymerizations by adding an inhibitor solution comprising a phenothiazine compound and/or a monoalkyl ether of hydroquinone to the free radical polymerizing system. The method is characterized in that the solvent of the inhibitor solution comprises at least 50% by weight of the solvent of alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of alkylene glycol and/or of polyalkylene glycol. The method permits the use of nontoxic inhibitor solutions. Inhibitor solutions are also described which comprise a phenothiazine compound and/or a monoalkyl ether of hydroquinone and, as solvent, alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of these compounds.

Abstract: An electrolyte-containing aqueous polymer solution is described with a salt content of 5% to 35% by weight with respect to the total weight of the polymer solution, containing at least one dissolved synthetic copolymer which contains structural units which are derived from (i) at least one amide of an ethylenically unsaturated carbonic acid and from (ii) at least one ethylenically unsaturated sulphonic acid or their alkali metal salts and/or ammonium salts, and containing at least one non-ionic surfactant selected from the group formed by alkoxylated fatty alcohols, alkoxylated alkylphenols and/or alkoxylated fatty acids, with the proviso that the mean degree of alkoxylation of said surfactants is 8-10. The aqueous polymer solution is used for the tertiary recovery of crude petroleum and is characterized by very good filtration behaviour, in particular in the presence of saline water.

Abstract: A method is described for immediately terminating free radical polymerizations by adding an inhibitor solution comprising a phenothiazine compound and/or a monoalkyl ether of hydroquinone to the free radical polymerizing system. The method is characterized in that the solvent of the inhibitor solution comprises at least 50% by weight of said solvent of alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of alkylene glycol and/or of polyalkylene glycol. The method permits the use of nontoxic inhibitor solutions. Inhibitor solutions are also described which comprise a phenothiazine compound and/or a monoalkyl ether of hydroquinone and, as solvent, alkylene glycol and/or polyalkylene glycol and/or terminally etherified derivatives of these compounds.