A method for stabilizing a natural rubber such as guayule. The method includes the step of introducing at least one of an Extraction Curves for Guayule Rubber Samples amine and a phenolic anti-oxidant, such as MADA, to a latex form of the rubber under conditions such that the anti-oxidant becomes chemically bound to the rubber. The method includes the further step of subsequently treating the rubber to remove at least a substantial portion of entrained resins. The method can yield a rubber composition of, for example, guayule rubber and including an anti-oxidant chemically bound thereto. The resultant rubber can be suitable for use in tire construction.

A modified conjugated diene-based polymer, and more particularly, a modified conjugated diene-based polymer having a unimodal molecular weight distribution curve measured by gel permeation chromatography (GPC), molecular weight distribution (PDI; MWD) of less than 1.7, and a Si content of 100 ppm or more based on weight, and including a repeating unit derived from an aromatic vinyl monomer in an amount from 15 wt % to less than 30 wt %, and a rubber composition including the same.

Provided are a method for preparing a nitrile-based rubber having an amount of ethylenically unsaturated nitrile of 34 wt % or less including preparing a polymer by performing a polymerization reaction by adding an ethylenically unsaturated nitrile-based monomer in two or more portions to a conjugated diene-based monomer, and coagulating the polymer by adding a sulfur-based coagulant to the polymer, and a nitrile-based rubber thus prepared having improved mechanical properties as well as excellent processability and low temperature characteristics.

Provided are a method for preparing a nitrile-based rubber having an amount of ethylenically unsaturated nitrile of 34 wt % or less including preparing a polymer by performing a polymerization reaction by adding an ethylenically unsaturated nitrile-based monomer in two or more portions to a conjugated diene-based monomer, and coagulating the polymer by adding a sulfur-based coagulant to the polymer, and a nitrile-based rubber thus prepared having improved mechanical properties as well as excellent processability and low temperature characteristics.

A vulcanizing composition useful for the vulcanization of vulcanizable formulations is disclosed. The vulcanizing composition includes a vulcanizing agent which in turn includes a cyclododecasulfur compound. A cyclododecasulfur compound characterized by a DSC melt point onset of between 155° C. and 167° C. when measured at a DSC heat rate of 20° C./minute is also disclosed.

A vulcanizing composition useful for the vulcanization of vulcanizable formulations is disclosed. The vulcanizing composition includes a vulcanizing agent which in turn includes a cyclododecasulfur compound. A cyclododecasulfur compound characterized by a DSC melt point onset of between 155° C. and 167° C. when measured at a DSC heat rate of 20° C./minute is also disclosed.

The purpose of the present invention is to provide: an anti-vibration rubber composition which enables the production of a hardened rubber article having excellent heat resistance, compression set, low dynamic magnification, tensile properties (elongation, strength), low-temperature properties and workability (scorch resistance); and an anti-vibration rubber which is produced by hardening the rubber composition. The anti-vibration rubber composition is characterized by comprising a rubber component mainly composed of a diene rubber, a bismaleimide compound as a vulcanizing agent, and N-phenyl-N-(trichloromethylthio)benzenesulfoneamide.

The purpose of the present invention is to provide: an anti-vibration rubber composition which enables the production of a hardened rubber article having excellent heat resistance, compression set, low dynamic magnification, tensile properties (elongation, strength), low-temperature properties and workability (scorch resistance); and an anti-vibration rubber which is produced by hardening the rubber composition. The anti-vibration rubber composition is characterized by comprising a rubber component mainly composed of a diene rubber, a bismaleimide compound as a vulcanizing agent, and N-phenyl-N-(trichloromethylthio)benzenesulfoneamide.

There is a process for high sulfur content copolymer preparation having the step of reacting sulfur in solid form with at least one crosslinker selected from organic compounds having at least a double or triple bond in the presence of at least one catalyst selected from dithiocarbamates, mercaptobenzothiazoles, xanthates, thiophosphates, at a temperature ranging from 110° C. to 180° C.

The high sulfur content copolymer, depending on the glass transition temperature, can be of elastomeric or thermoplastic type and can be advantageously used in different applications. In case of an elastomeric-type high sulfur content copolymer, the copolymer can be advantageously used in different applications such as, for example, thermal insulation, conveyor belts, transmission belts, flexible tubes, elastomeric tire compositions. In case of a thermoplastic-type high sulfur content copolymer, the copolymer can be advantageously used, as such or in a mixture with other (co)polymers (for example, styrene, divinylbenzene), in different applications such as, for example, packaging, electronics, household appliances, computer cases, CD cases, kitchen, laboratories, offices and medical items, in building and construction.

Processes for forming a vulcanizable elastomeric formulation are disclosed. The processes include the steps of mixing an elastomer with a vulcanizing agent to form a vulcanizable elastomeric formulation that includes the vulcanizing agent dispersed in the elastomeric compound, wherein the vulcanizing agent includes a cyclododecasulfur compound. A process for forming a vulcanized elastomeric article is also described.