Styrene-butadiene rubber: properties, application, formula

Styrene-Butadiene rubber is one of the most used options of polymeric materials. It is suitable for the manufacture of tires and other rubber products with high quality.

Named polymeric material is produced from inexpensive raw materials, and its fabrication technology is considered to be quite affordable, with a clear algorithm of actions. The resulting styrene-butadiene rubber has an excellent performance and chemical characteristics. It is produced in substantial quantities and provided by the manufacturer in a wide range.

Raw materials for production

Let us Consider the production of butadiene-styrene rubbers. As a source of raw materials for the polymer material choose butadiene-1,3 or alpha-methylsterol. Get styrene butadiene rubber by solution or emulsion copolymerization. In the second method, are formed of styrene-butadiene rubbers mortar.

Emulsion polymerization

How did they obtain styrene-butadiene rubber? The reaction involves the joint polymerization of styrene and butadiene in emulsion. The final product obtained as a result of this interaction, called styrene-butadiene rubber (SKS).

Currently in the domestic rubber industry is the production of a variety of polymer products based on this chemical substance.

As divided styrene-butadiene rubber? Manufacturers offer the following options:

• Rubbers that do not contain oil (SKS-SOARC);
• Materials with an average percent oil content (SKM-SALRM-15);
• With a high amount of oil (SKS-STRCM-27);
• With excellent dielectric characteristics (SKS-SOARED).

Specific names

The First digit in the names tell you about the quantitative content of styrene in the starting material selected for conducting the polymerization process:

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• “And” implies a process of low-temperature polymerization (no more than 5 degrees).
• “M” indicates that it is oil, not only styrene.
• Styrene-Butadiene rubber with the letter “R” talks about conducting the polymerization reaction without the presence of the regulator.
• “To” points to the use in the manufacture of rubber rosin emulsifier.
• The Letter “P” symbolizes the material obtained in the presence of the original salt mixture of fatty synthetic acids, which are products of partial oxidation of saturated paraffins.

What is styrene-butadiene rubber? Getting it is based on the polymerization process, which is familiar even to the students studying in schools and colleges.

So, for the production of plantar rubber industry used malonarushennye styrene-butadiene rubber, the formula of which is no different from conventional diene hydrocarbon. Have rubbers produced on the basis of styrene-butadiene resin, increased resistance to mechanical abrasion, good leather-like characteristics.

The process of emulsion polymerization in the special industrial installation. What characterized this styrene-butadiene rubber? Getting it is on a clear and proven technology. The average duration of a chemical reaction is 12-15 hours. After completion of the polymerization, the latex is formed, which contains approximately 30-35 percent of the polymer material. As an antioxidant, the latex is injected neon.

Latex rubber is produced by coagulation of electrolytes which contain sulfuric acid. Considering that the role of emulsifiers are kanifolno oil and soap created on the basis of synthetic fatty acids, in addition to coagulation, there is also the formation of fatty acids that have a positive effect on the technological characteristics of the finished product.

With the addition of sulfuric acid converts the Soaps into free organic acids, the coagulation of the latex formed of butadiene-styrene rubber. Ready to use versatile material depends on the type of production. Basically rubber is a common raw material in the chemical industry.

Structure rubber

What is the structure of styrene-butadiene rubber? The physical properties of the substance is determined by the peculiarities of its structure. Upon receipt of the polymer by sozialarbeit, a polymer of irregular structure. The rubber monomer units are random, the molecule has a branched appearance.

Almost 80 percent of all units have the TRANS-configuration, and only 20 percent is characterized by a CIS-structure.

Features

Analyze the styrene-butadiene rubber. The properties of this substance are connected with its high molecular weight. On average it is 150 000-400 000. And the technology of manufacturing oil-filled rubbers involves the selection of materials with a higher relative molecular mass. Such an option allowsto eliminate the negative effect of oil on rubber quality to keep for a long period of great technological characteristics of rubber.

From ethylene to styrene-butadiene rubber, having a technological chain with the use of activators, emulsifiers, regulators, and other substances, partly in the communication process go into the composition of the produced rubber.

Distinctive features

Characterization of styrene-butadiene rubber. The formula of this substance indicates that it is stable to mechanical deformations of aggressive solvents. To increase frost resistance and elasticity of rubber reduced in the starting mixture, the amount of styrene. The resulting polymer is soluble in gasoline and aromatic solvents.

What else stands out for styrene-butadiene rubber? Properties and relation to concentrated acids, ketones, alcohol stable, besides, polymer with excellent gas and water permeability. During the heating of the rubber, there are serious structural changes, which adversely affects the physico-mechanical properties of the resultant rubber.

Thermal oxidation at temperatures from 125 °C causes a decrease in stiffness and degradation. Subsequent oxidation involves strong structuring of the polymer affects the increase in its rigidity.

Features

To create a rubber compound used is styrene-butadiene rubber. Properties, use of this agent class of diene hydrocarbons in full compliance with the characteristics of its structural formula.

The presence of the phenyl side groups affects of increased resistance to the negative effects of radiation exposure in comparison with other varieties of these polymers.

The rubber mixtures, which are made on the basis of styrene-butadiene rubber, low adhesion, high shrinkage and kalandrovym the inside. This has a negative impact on the implementation of technological processes, as well as during gluing (assembling) of workpieces of rubber products.

Low-temperature rubbers Have improved processing properties, they are called “hot” rubbers.

Varieties of rubbers

Soft styrene-butadiene rubber low temperature have a low viscosity, so they are not plasticit.

Hard rubber produced in small quantities, by exposing them to a thermal plasticizing in air at a temperature of about 1400 °C with the use of activators of the process of destruction.

Unfilled vulcanizers low tensile strength. When you reduce the amount of the bound styrene in the polymer compound decreases resistance and abrasion resistance, increases frost resistance, increases elasticity.

Sazhenapolnennoy (with carbon black), a vulcanizer styrene-butadiene rubbers have excellent parameters of thermal resistance and durability, but in some degree they are inferior in elasticity and deformation resistance of conventional rubbers. Used presses have additional resistance to concentrated and diluted acids, alcohols, alkalis, esters. In solvents of rubber they swell.

All the polymers used in the manufacture of tires, the production of a variety of non-molded and molded products. For example, from styrene-butadiene rubber made conveyor belt for timber production, produce rubber footwear. In connection with increased radiation resistance these rubbers are used in the manufacture of rubbers, having an optimal resistance to gamma radiation.

For the manufacture of products, which have excellent cold resistant characteristics, used raw materials, in which the minimum styrene content.

Characteristics of butadiene-styrene rubbers, soluble polymerization

In the domestic industry launched production of styrene-butadiene rubber solution polymerization having different styrene content:

• ROSC-10.
• ROSC-25.
• ROSC-18.
• ROSC-50.
• ROSC-25D (has high dielectric characteristics).

In the sale is a rubber, which includes mikroblogi aromatic styrene, is intended for processing by moulding.

In addition, there are rubber-filled mortar polymerization, which contain up to 27% oil. Thanks to soluble polymerization in the presence of organolithium catalysts is carried out adjustment of basic parameters of molecular structure:

• Branching chain;
• Molecular weight;
• Macrostructure.

Distinctive characteristics of such rubbers consider essential the presence of the polymer (98%), the minimum number of impurities. The polymers have a linear structure in comparison with the styrene-butadiene rubbers of emulsion.

The resulting polymeric materials of higher ductility, wear resistance, frost resistance, high resistance to cracking. Note and high dynamic endurance of these materials. With less shrinkage they have greater viscosity according to Mooney, as the macromolecules have a linear structure, which can be filled with a large number of soot (technicalcarbon) and oil without any negative changes of mechanical and physical properties of vulcanizers.

There are some technological advantages in the production of mortar rubbers in comparison with inorganic options, but it is much more requirements to the purity of the used monomers. Use rubber solution polymerization in the tire industry, to create a durable conveyor belts, Shoe soles, rubber sleeves, numerous rubber items. Starting components for the production of polymeric materials of this type believe styrene and butadien-1,3. Get the mortar or rubbers by emulsion copolymerization.

Modern production is not only manufacturing technology unfilled rubbers, but the production of polymers, a composition which contains resin, carbon black, oil. Among all the manufactured polymer materials to share styrene-butadiene rubber accounts for more than half of the production capacity.

The Reason for this scale lies in the high uniformity of the physical and chemical characteristics of the produced product, availability of the original monomers (styrene and butadiene), as well as established production lines.

A Large mass of styrene-butadiene rubber in production today is produced by emulsion copolymerization of styrene and butadiene.

Classification of rubbers on the structure

Subject to the conditions of the polymerization and composition of the used components launched production of styrene-butadiene rubbers which differ in properties and composition. Allowed for statistical, irregular distribution of the structural units of styrene and butadiene in the macromolecule.

With decreasing temperature, a decrease in the quantitative content in the generated low molecular weight rubber fractions. Furthermore, there is a structural reduction in branching, increase in the regular structure of the polymer that is positively reflected in the technical and operational characteristics of finished products.

The development of domestic production of synthetic materials the important point was the establishment of the production of butadiene-styrene materials by polymerization by a radical mechanism. Currently, such materials of high quality and at a reasonable price produced Krasnoyarsk, Omsk, Togliatti, Sterlitamak, Voronezh.

Technology Features

At desire it is possible to obtain a polymer having certain parameters. For example, with a given average molecular weight, which is adjustable as by entering a polymerization regulators capable of chain transfer. Increasing the quantitative content of the regulators there was a decrease of the molecular weight of the polymer.

What can be seen as emulsifiers that are suitable for the production of stable emulsions of monomers, and for creating the final products of polymerization, latexes? The main chemical components consider potassium or sodium salts of synthetic fatty carboxylic acids, gidrirovannoe rosin, salts Alisultanov.

When choosing a rosin it is first subjected to special treatment. In the process of disproportionation with the catalyst (palladium) it acquires the properties necessary for the production chain rubbers.

Speficic production

To conduct a copolymerization using a battery of curing. In the preparation of charge mix of purified and dried styrene, butadiene, solvent (this may be cyclohexane) in the ratio of 5/1. Further components of the initial charge is served in a diaphragm mixer for high quality mixing. The mixture is then directed to a chemical fine polishing of a variety of small impurities.

The device is fed organolithium compounds, titrated at a temperature of 25 °C for 20 minutes. The degree of purification is determined by the color of the charge. If there are no impurities, the mixture is slightly brown. To the polymerization batch is mixed with the catalyst, the polar additives.

The Process is carried out in the battery, which consists of three standard devices, by successive filing of the charge. The temperature inside the curing is maintained in the range from 50 to 80 °C. the Average duration of the whole chemical process is 6 hours.

Conclusion

In every sphere of life and activity in a timely man, there are materials, which are based on styrene-butadiene rubber. First, we note the creation of rubber outsoles for shoes, rubber car tires, a variety of hoses.

Statistical copolymers of styrene and butadiene is widely used in the creation of electrical insulating materials, various products for the automotive industry, including the creation of high-quality tires. Innovative technologies that use modern manufacturers styrene-butadiene rubbers, and allow them to create products with specified physical and chemical parameters, the desired performance characteristics.

Among the features of this production will celebrate the use of catalysts of high quality. Depending on the structure of the synthesized rubbers are significantly different duration of the process of their creation, as well as the final cost produced on the basis ofrubber rubber production.