Abstract: A conjugated diene copolymer comprising (A) 40 to 90 mole % of a conjugated diene component, (B) 0.5 to 10 mole % of an alpha,beta-ethylenically unsaturated carboxylic acid component, (C) 0.1 to 5 mole % of a polyfunctional alkenyl compound component and (D) 5 to 58 mole % of a monoolefinically unsaturated compound component wherein the intrinsic viscosity [.eta.] of the copolymer as measured at 30.degree. C. in dimethylformamide is 0.01 to 3.0 dl/g, the width (.DELTA.Tg) of the endothermic transition temperature section determined by a differential scanning calorimetry is 45.degree. to 120.degree. C., and the limit temperature (T.sub.1) on the lower temperature side of the endothermic transition temperature section is -40.degree. C. or less.

Abstract: A conjugated diene copolymer comprising (A) 40 to 90 mole % of a conjugated diene component, (B) 0.5 to 10 mole % of an alpha,beta-ethylenically unsaturated carboxylic acid component, (C) 0.1 to 5 mole % of a polyfunctional alkenyl compound component and (D) 5 to 58 mole % of a monoolefinically unsaturated compound component wherein the intrinsic viscosity [.eta.] of the copolymer as measured at 30.degree. C. in dimethylformamide is 0.01 to 3.0 dl/g, the width (.DELTA.Tg) of the endothermic transition temperature section determined by a differential scanning calorimetry is 45.degree. to 120.degree. C. and the limit temperature (T.sub.1) on the lower temperature side of the endothermic transition temperature section is -40.degree. C. or less.

Abstract: Methacrylic acid is produced from methacrolein by gaseous phase oxidation in a very high selectivity, when methacrolein, molecular oxygen-containing gas and steam in a molar ratio of methacrolein:molecular oxygen:steam of 1:1-3:0-50 are subjected to reaction at a temperature in the range of 250.degree. to 400.degree. C., at a space velocity of 250 to 3,000 hr.sup.-1 (at 0.degree. C. and 1 atm.) with a novel catalyst having the following composition formula in atomic ratio:Mo.sub.a P.sub.b Zr.sub.c V.sub.d Mn.sub.e X.sub.f O.sub.gwherein X represents at least one member selected from the group consisting of potassium, rubidium, cesium and thallium, and a, b, c, d, e, f or g represents the number of atoms of Mo, P, Zr, V, Mn, X or O, respectively, and when a is 12, b is 0.5 to 5, c is 0.1 to 5, d is 0.05 to 3, e is 0.05 to 1.5, f is 0.1 to 3 and g is 40 to 60; and g is a number sufficient enough to satisfy the valencies of the respective catalyst component elements.