Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of a mixture comprising: A) at least one stable hindered nitroxyl compound having the structural formula: wherein R1 and R4 are independently selected from the group consisting of hydrogen, alkyl, and heteroatom-substituted alkyl and R2 and R3 are independently selected from the group consisting of alkyl and heteroatom-substituted alkyl; and X1 and X2 (1) are independently selected from the group consisting of halogen, cyano, COOR7, —S—COR7, —OCOR7, (wherein R7 is alkyl or aryl), amido, —S—C6H5, carbonyl, alkenyl, or alkyl of 1 to 15 carbon atoms, or (2) taken together, form a ring structure with the nitrogen; and B) at least one inhibitor selected from the group consisting of ortho-quinone, ortho-hydroquinone, para-quinone, para-hydroquinone, and derivatives of the foregoing.

Abstract: An improved process for the production and purification of unsaturated monomers employing nitroxyl-containing inhibitors wherein process streams containing the inhibitor are recycled is disclosed, wherein the improvement comprises recycling said streams at a reboiler temperature no higher than about 110° C.

Abstract: Disclosed herein is a method for inhibiting the premature polymerization of ethylenically unsaturated monomers comprising adding to said monomers an effective amount of a mixture comprising:

Abstract: A nitroaromatic compound is used to enhance the solubility of a nitroxyl compound in an aromatic hydrocarbon solvent.

Abstract: An improvement in a method for evaluating the efficiency of polymerization inhibitors is disclosed, wherein the improvement comprises: A) producing dissolved polymer in a solution comprising monomer and at least one inhibitor by means of any test known in the art to be useful for evaluating polymerization inhibitors, B) collecting the polymer-containing solution, C) measuring the degree of polymerization of the monomer in the collected solution, and D) re-subjecting the polymer-containing solution to the test conditions of A).

Abstract: A method for evaluating the polymer growth inhibition ability of a compound or compounds is disclosed wherein the method comprises:A) weighing a dry seed of insoluble polymer capable of growing via a living polymerization mechanism;B) subjecting the seed of insoluble polymer to conditions capable of causing a living polymer to grow via a living polymerization mechanism;C) drying the seed; andD) weighing the seed a second time to determine any increase in weight;wherein the polymer growth inhibition ability of the compound or compounds is inversely proportional to any increase found in weight of the seed.

Abstract: A non-yellowing antioxidant-UV stabilizer combination especially useful in AES polymers comprising(A) at least one antioxidant selected from the group consisting of:(i) a thiodialkylene bis-(3,5-dialkyl-4-hydroxy) hydrocinnamate antioxidant;(ii) An N,N'-alkylene bis-(3,5-dialkyl-4-hydroxy) hydrocinnamamide antioxidant;(iii) an O,O-dialkyl-3,5-dialkyl-4-hydroxybenzyl phosphonate antioxidant;(iv) an oxamidobis alkyl (3,5)-dialkyl-4-hydroxyphenyl) propionate antioxidant; and(v) a [3-(3,5-dialkyl-4-hydroxyphenyl)propionamido]alkyl stearate antioxidant; and(B) a UV stabilizer package comprising:(vi) at least one UV stabilizer of the hindered amine type, with or without(vii) at least one UV absorber.