Abstract: A heat-resistant copolymer obtained by copolymerizing (A) 72-82 parts by weight of .alpha.-methylstyrene and (B) 26-18 parts by weight of acrylonitrile, characterized in that the copolymer contains (a) 0-15% by weight of monomer chain 13 (A)-(A)-(A)--, (b) 50% by weight or more of monomer chain --(A)-(A)-(B)--, and (c) 50% by weight or less of monomer chain --(B)-(A)-(B)--, the total of (a), (b) and (c) being 100% by weight. This copolymer is excellent in heat stability and moldability when molded at high temperatures, and the blending of this copolymer with other thermoplastic resins gives thermoplastic resins with excellent heat resistance.

Abstract: A heat-resistant copolymer obtained by copolymerizing (A) 72-82 parts by weight of .alpha.-methylstyrene and (B) 26-18 parts by weight of acrylonitrile, characterized in that the copolymer contains (a) 0-15% by weight of monomer chain --(A)--(A)--(A)--, (b) 50% by weight or more of monomer chain --(A)--(A)--(B)--, and (c) 50% by weight or less of monomer chain--(B)--(A)--(B)--, the total of (a), (b) and (c) being 100% by weight. This copolymer is excellent in heat stability and moldability when molded at high temperatures, and the blending of this copolymer with other thermoplastic resins gives thermoplastic resins with excellent heat resistance.

Abstract: A rubber composition consisting essentially of a dispersion in which particles of a high-melting isotactic poly-.alpha.-olefin having a melting point of at least 150.degree. C. are uniformly dispersed in a rubber matrix, said particles having an average particle size of not more than 200.mu., has a high modulus of elasticity and also excellent tear resistance. Such rubber composition can be obtained, for example, by mixing fine powder of said isotactic poly-.alpha.-olefin having an average particle size of not more than 200.mu. with a rubber solution, dispersing the particles uniformly in said rubber solution and recovering a rubber composition from the dispersion.

Abstract: A novel rubber compound which comprises 100 parts by weight of a rubber component (I), 0.1-15 parts by weight of an amine salt of carboxylic acid (II) and 0-7 parts by weight of sulfur (III), said rubber component (I) consisting of 40-100% by weight of an elastomeric copolymer (A) and 60-0% by weight of a vulcanizable rubber (B); said elastomeric copolymer (A) being composed of a C.sub.4 or C.sub.5 conjugated diene, styrene and a glycidyl group-containing monomer; the amount of said conjugated diene, the total amount of said conjugated diene and said styrene and the amount of said glycidyl group-containing monomer being 50% by weight or more, 80-99.5% by weight and 0.5-20% by weight, respectively, based on the weight of said elastomeric copolymer (A); and the content of said glycidyl group-containing monomer in said rubber component (I) being 0.

Abstract: A rubber composition comprising (A) 100 parts by weight of a rubber; (B) 5 to 50 parts by weight of a low molecular weight diene copolymer containing a glycidyl group-containing monomer or chloromethylstyrene, said copolymer (B) comprising 30% by weight or less of copolymerized styrene, and having an intrinsic viscosity of 0.2 to 1.3 dl/g as measured in toluene at 30.degree. C.; (C) a crosslinking agent reactive with the glycidyl group or the chloromethyl group in the copolymer (B) selected from (C.sub.I) a metallic oxide and (C.sub.II) an amine compound; and (D) 0.2 to 7 parts by weight, per 100 parts by weight of the rubber (A), of sulfur. This rubber composition has a good processability and can give a vulcanizate having excellent physical properties.

Abstract: A novel rubber compound which comprises 100 parts by weight of a rubber component (I), 0.1-15 parts by weight of an amine salt of carboxylic acid (II) and 0-7 parts by weight of sulfur (III), said rubber component (I) consisting of 40-100% by weight of an elastomeric copolymer (A) and 60-0% by weight of a vulcanizable rubber (B); said elastomeric copolymer (A) being composed of a C.sub.4 or C.sub.5 conjugated diene, styrene, and a glycidyl group-containing monomer; the amount of said conjugated diene, the total amount of said conjugated diene and said styrene and the amount of said glycidyl group-containing monomer being 50% by weight or more, 80-99.5% weight and 0.5-20% by weight, respectively, based on the weight of said elastomeric copolymer (A); and the content of said glycidyl group-containing monomer in said rubber component (I) being 0.

Abstract: When an elastomeric copolymer of a C.sub.4 or C.sub.5 conjugated diene and an aromatic vinyl compound is brominated in latex while keeping the uniformity of the latex until the amount of bormine combined with the copolymer reaches 0.5-15% by weight, the resulting brominated conjugated diene-aromatic vinyl compound rubber contains 3-80% by weight of a toluene-insoluble fraction formed by the bromination and has a high green strength and a good processability. A vulcanized rubber obtained from said brominated rubber has a high modulus of elasticity and a high tensile strength. When an anionic surfactant is used as an emulsifier, the uniformity of the above-mentioned latex can be kept by adjusting the pH value of the bromination reaction system to 9 or highter, preferably 10 or higher, during the reaction or by auxiliarily adding a nonionic surfactant. When a cationic or nonionic surfactant is used as an emulsifier, regulation of pH is unnecessary.