Abstract: High amounts of silicon dioxide are readily incorporated into an emulsion polymerized elastomer by mixing an aqueous dispersion of silicon dioxide with a latex of the emulsion polymer and subsequently spray drying the mixture. Free flowing, fine-size (e.g., less than 500 micrometers) particles are produced with generally complete incorporation of silicon dioxide. The presence of the silicon dioxide permits rubbers with low gel and/or low Mooney viscosity to be spray dried whereas previously this could not be accomplished. Compared to conventional means of adding a silica to a bale rubber, the above powdered masterbatch gives shorter mixing times with lower power consumption with improved physical properties, such as tensile strength.

Abstract: High amounts of silicon dioxide are readily incorporated into an emulsion polymerized elastomer by mixing an aqueous dispersion of silicon dioxide with a latex of the emulsion polymer and subsequently spray drying the mixture. Free flowing, fine-size (e.g., less than 500 micrometers) particles are produced with generally complete incorporation of silicon dioxide. The presence of the silicon dioxide permits rubbers with low gel and/or low Mooney viscosity to be spray dried whereas previously this could not be accomplished. Compared to conventional means of adding a silica to a bale rubber, the above powdered masterbatch gives shorter mixing times with lower power consumption with improved physical properties, such as tensile strength.

Abstract: A random copolymer is formed by emulsion polymerization from two monomeric classes. The first monomeric class is a conjugated diene or substituted conjugated diene containing from four to about eight carbon atoms. The second monomeric class is of the general formulaCH.sub.2 .dbd.CHR.sub.1 CXwherein R.sub.1 is hydrogen or an alkyl group containing from 1 to about 4 carbon atoms and X is --OOR.sub.2, --ONR.sub.3 R.sub.4, or --OOR.sub.7 OR.sub.2. R.sub.2 is an alkyl group containing from 1 to about 4 carbon atoms, --CH.sub.2 CF.sub.3 or --CH.sub.2 CF.sub.2 CF.sub.2 H. R.sub.3 and R.sub.4 are alkyl groups independently containing from 1 to about 4 carbon atoms and R.sub.7 is an alkylene group containing from 1 to about 4 carbon atoms.The second monomeric class can be replaced with up to about 20 percent by weight of the general formula ##STR1## wherein R.sub.5 is an alkenyl group containing from about 2 to about 8 carbon atoms and R.sub.6 is hydrogen or an alkyl group containing from 1 to about 8 carbon atoms.

Abstract: A preferred carboxylated nitrile rubber is prepared by polymerizing a diene, a nitrile and a small amount of an acrylic acid, which rubber has distributed therethrough an amount of alkyl or alkenyl monocitrate to obtain improved scorch time and reduced cure time.

Abstract: Compositions containing diene/nitrile polymers having active halogen sites are cured using zinc oxide and a thiourea compound to yield vulcanizates having excellent heat resistance.