Butadiene-styrene rubber: properties, application, formula

Butadiene-styrene rubber is considered one of the most used options for polymeric materials. It is suitable for the production of tires and other rubber products having high quality.

The named polymeric material is made from inexpensive raw materials, and the technology of its manufacturing is considered quite accessible, having a clear algorithm of actions. The resulting butadiene-styrene rubber has excellent operational and chemical characteristics. It is produced in significant quantities and is presented by the manufacturer in a wide range.

Raw materials for production

Let us consider in detail the production of butadiene-styrene rubbers. As a starting material for this polymeric material, butadiene-1,3 or alpha-methylstyrene is chosen. The butadiene-styrene rubber is obtained by solution technology or by emulsion copolymerization. In the second method, butadiene-styrene solution rubbers are formed.

Emulsion polymerization

How is the production of butadiene-styrene rubber? The reaction involves co-polymerization of styrene and butadiene in the emulsion. The final product, obtained as a result of this interaction, is called butadiene-styrene rubber (SCS).

At the moment, the domestic rubber industry produces a variety of polymer products based on this chemical.

How is styrene-butadiene rubber classified? Manufacturers offer the following options:

• Rubbers that do not contain oil (SCS-ZOARK);
• Materials with an average percentage of oil (SCM-ZOLRKM-15);
• With increased amount of oil (SCS-ZODRKM-27);
• With excellent dielectric characteristics (SCS-ZOARPD).

Specificity of the name

The first figures in the given names tell about the quantitative content of styrene in the initial charge, chosen for the polymerization process:

• "A" involves the implementation of a low-temperature polymerization process (no more than +5 degrees).
• "M" indicates that it contains oil, not only styrene.
• Butadiene-styrene rubber with the letter "R" tells about the polymerization reaction without the presence of a regulator.
• "K" indicates the use of a rosin emulsifier in the manufacture of rubber.
• The letter "P" symbolizes the material obtained by the presence in the initial mixture of salts of fatty, synthetic acids, which are products of partial oxidation of saturated paraffins.

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

So, for the production of plantar rubbers in the industry, resin-filled butadiene-styrene rubber is used, the formula of which is no different from the usual diene hydrocarbon. Rubbers produced on the basis of butadiene-styrene resin, increased resistance to mechanical abrasion, good skin-like characteristics.

The process of emulsion polymerization is carried out in a special industrial plant. What is the characteristic of this styrene-butadiene rubber? Receiving it is carried out on a clear and proven technology. The average duration of a chemical reaction is 12-15 hours. After the polymerization is complete, a latex is formed, which contains about 30-35 percent of the polymer substance. As an antioxidant, latex is injected with neon D.

From latex, rubber is produced by coagulation of electrolytes that contain sulfuric acid. Considering that rosin oil and soap created on the basis of fatty synthetic acids act as emulsifiers, in addition to coagulation, the formation of fatty acids, which have a positive effect on the technological characteristics of the finished product, is also observed.

Thanks to the addition of sulfuric acid, soap is converted into free organic acids, coagulation of latex is completed and styrene-butadiene rubber is formed. The use of the finished material is multifaceted, depends on the type of production. Basically, rubber is a common raw material in the chemical industry.

Structure of rubber

What is the structure of styrene butadiene rubber? The physical properties of a given substance are determined by the peculiarities of its structure. When the polymer is prepared by ozonization, a polymer of an irregular structure is formed. In rubber, monomeric units are randomly distributed, the molecule has a branched appearance.

Almost 80 percent of all links have a trans-configuration, and only 20 percent is characterized by a cis structure.

Characteristics

Let's analyze butadiene-styrene rubber. The properties of this substance are associated with its high molecular weight. On average, it is 150 000-400 000. And the technology of manufacturing oil-filled rubbers assumes the choice of materials with a high index of relative molecular weight. This option allows you to eliminate the negative impact of oil on the quality of rubber, keep for a long period of excellent technological characteristics of rubber.

It is possible to produce butadiene-styrene rubber from ethylene by carrying out a technological chain with the use of activators, emulsifiers, regulators, as well as other substances, partially in the process of interaction, passing into the composition of the formed rubber.

Distinctive characteristics

We characterize butadiene-styrene rubber. The formula of this substance indicates that it is resistant to mechanical deformation, aggressive solvents. To increase the frost resistance and elasticity of rubber, the amount of styrene in the starting mixture is reduced. The resulting polymer dissolves in gasoline and aromatic solvents.

What else does styrene-butadiene rubber stand out? Properties and ratio to concentrated acids, ketones, alcohol is stable, besides the polymer has excellent gas and water permeability. When the rubber is heated, serious structural changes are observed, which negatively affects the physicomechanical properties of the resulting rubber.

Thermal oxidation at temperatures from 125 ° C causes a decrease in stiffness and destruction. The subsequent oxidation involves a serious structuring of the polymer, which affects the increase in its rigidity.

Application Features

To create a rubber mixture it is used butadiene-styrene rubber. Properties, the use of this representative of the class of diene hydrocarbons fully corresponds to the features of its structural formula.

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

Rubber compounds that are made on the basis of butadiene-styrene rubbers, low tackiness, increased shrinkage during calendering and syringing. This negatively affects the implementation of technological processes, as well as when carrying out gluing (assembling) of blanks of rubber products.

The low-temperature rubbers have improved technological properties, they are called "hot" rubbers.

Varieties of rubbers

Soft butadiene-styrene low-temperature rubbers have a low viscosity, so they are not plasticized.

Rigid rubbers are produced in small amounts, subjecting them to thermal-oxidative plasticization in air at a temperature of the order of 1400 ° C using activators of the destruction process.

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

Saturated (with technical carbon) vulcanizers of butadiene-styrene rubbers have excellent parameters for heat resistance and wear resistance, but to a certain extent they are inferior in terms of elasticity and deformation resistance to conventional rubbers. Used vulcanizers have additional resistance to concentrated and diluted acids, alcohols, alkalis, ethers. In rubber solvents they swell.

All obtained polymers are used in the production of tires, the manufacture of a variety of non-molded and molded products. For example, conveyor belts for timber production are manufactured from styrene butadiene rubber, rubber shoes are produced. Due to the increased radiation resistance, all these rubbers are used in the manufacture of rubbers having optimum resistance to gamma radiation.

For the production of products characterized by excellent frost-resistant characteristics, raw materials are used, in which the minimum content of styrene.

Characteristics of butadiene-styrene rubber of solution polymerization

In the domestic industry, the production of butadiene-styrene solutions of solution polymerization having different styrene contents is arranged:

• RSCC-10.
• RSCC-25.
• RSCC-18.
• ДССК-50.
• ДССК-25Д (possesses the raised dielectric characteristics).

On sale there is also a rubber, which includes microblocks of aromatic styrene, is intended for processing by casting.

In addition, there are also oil-filled rubber solutions, which contain up to 27% oil. Due to solution polymerization, in the presence of organolithium catalysts, the main parameters of the molecular structure are regulated:

• Chain branching;
• Molecular weight;
• Macrostructure.

The distinctive characteristics of such rubbers are the substantial presence of the polymer itself (up to 98%), the minimum amount of impurities. Polymers have a linear structure in comparison with butadiene-styrene emulsion rubbers.

The resulting polymeric materials have higher plasticity, wear resistance, frost resistance, increased resistance to cracking. We also note the high dynamic endurance of these materials. With less shrinkage, they have a higher Mooney viscosity, since macromolecules have a linear structure, are capable of filling with a large amount of carbon black (technical carbon) and oil without a negative change in the mechanical and physical properties of vulcanizers.

There are some technological advantages in the production of solution rubbers in comparison with emulsion variants, but there is much more demand for the purity of monomers used. Use rubber solutions of polymerization in the tire industry, to create strong conveyor belts, shoe soles, rubber sleeves, numerous rubber parts. The initial components for the production of polymeric materials of this type are styrene and bouadien-1,3. Rubbers are prepared by solution or emulsion copolymerization.

In modern production, not only the technology of manufacturing uncompleted rubbers is used, but also the production of polymers, in which resin, technical carbon, and oil are present. Among all produced polymeric materials, butadiene-styrene rubber accounts for more than half of all production capacities.

The reason for this scale lies in the high homogeneity of the physical and chemical characteristics of the product, the availability of the starting monomers (styrene and butadiene), as well as the established technological line.

A large mass of styrene-butadiene rubber in modern production is obtained by emulsion copolymerization of styrene and butadiene.

Classification of rubbers by structure

Taking into account the polymerization conditions and the composition of the components used, the production of butadiene-styrene rubbers has been established, which differ in properties and composition. A statistical, irregular distribution of structural units of styrene and butadiene in a macromolecule is allowed.

When the temperature is lowered, the quantitative content of the low molecular weight fractions in the rubber is reduced. In addition, there is a decrease in structural branching, an increase in the regular structure of the polymer, which positively affects the technical and operational characteristics of the finished product.

In the development of domestic production of synthetic materials, the important factor was the establishment of production of butadiene-styrene materials by polymerization by a radical mechanism. At present, such materials of high quality and at an affordable price are produced at the plants of Krasnoyarsk, Omsk, Togliatti, Sterlitamak, Voronezh.

Technology features

If desired, it is possible to obtain a polymer having certain parameters. For example, with a given average molecular weight, which is regulated as the polymerization proceeds by introducing regulators capable of chain transfer. As the quantity of regulators increases, a decrease in the molecular weight of the polymer is observed.

What can be considered as emulsifiers suitable for the production of persistent emulsions of monomers, as well as for the creation of final polymerization products, latexes? As the main chemical components, potassium or sodium salts of fatty synthetic carboxylic acids, hydrogenated rosin, and salts of alkyl sulfonates are considered.

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

Production Slicer

A battery of polymerizers is used for copolymerization. When preparing the charge mix purified and pre-dried styrene, butadiene, solvent (it can be cyclohexane) in the ratio 5/1. Further, the components of the initial charge are fed into the diaphragm mixer for high-quality mixing. Then the mixture is sent to chemical fine cleaning from a variety of fine impurities.

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

The process is carried out in a battery, which consists of three standard apparatuses, by the sequential feeding of the charge. The temperature inside the polymerizers is maintained in the range of 50 to 80 ° C. The average duration of the entire chemical process is 6 hours.

Conclusion

In any sphere of life and activity of a timely person, materials are found, based on styrene-butadiene rubber. First of all, we note the creation of rubber soles for shoes, automobile rubber tires, various watering hoses.

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

Among the features of this production, we note the use of high quality catalysts. Depending on the structure of synthesized rubbers, the duration of the process of their creation differs substantially, as well as the final cost of the rubber products produced on the basis of rubber.