Research on styrene-butadiene rubber_industrial additives

Styrene-butadiene rubber (SBR), also known as polystyrene-butadiene copolymer. Its physical structure properties, processing properties and product performance are close to those of natural rubber. Some properties such as wear resistance, heat resistance, aging resistance and vulcanization speed are better than those of natural rubber. It can be used with natural rubber and various synthetic rubbers and is widely used. It is used in the production of tires, tapes, hoses, wires and cables, medical equipment and various rubber products. It is the largest general-purpose synthetic rubber variety and one of the earliest rubber varieties to achieve industrial production.

According to the polymerization process, styrene-butadiene rubber can be divided into emulsion polystyrene-butadiene rubber (ESBR) and solution polystyrene-butadiene rubber (SSBR).

Emulsion polystyrene-butadiene rubber is composed of butadiene and styrene as the main monomers, and is supplemented with other auxiliary chemical raw materials. Under certain process conditions, it is polymerized by emulsion method to first generate styrene-butadiene slurry. After removing unconverted monomers from the glue, product glue is produced through processes such as coagulation and drying.

Solution-polymerized styrene-butadiene rubber is a polymer glue made from butadiene and styrene as the main monomers. In a hydrocarbon solvent, an organic lithium compound is used as an initiator to initiate anionic polymerization. After adding additives such as antioxidants, the product glue is produced through processes such as coagulation and drying.

The raw materials and configurations of the two production methods of solution-polymerized styrene-butadiene rubber and emulsion-polymerized styrene-butadiene rubber are basically the same. The main raw materials are butadiene and styrene, but dozens of auxiliaries are needed in the emulsion polymerization process. The solution-polymerized styrene-butadiene rubber only needs alkyl lithium as a catalyst and a small amount of additives. The solution preparation is simple and easy to operate. Moreover, the molecular weight of solution-polymerized random styrene-butadiene rubber is small and can be filled with a large amount of carbon black and ink. At the same time, it does not need to be masticated, has good low-temperature properties, and has small permanent deformation. It does not need to use plasticizers and is easier to wrap. After adding raw materials, it is easy to form into a strip. The film is very smooth, has small shrinkage, and the processing process is also relatively simple. It is safe and has a much larger mixing capacity than latex polystyrene butadiene rubber.

Improvement of performance of styrene-butadiene rubber – carbon black filling

The organic host of coal Structural units include aromatic core centers, side chain functional groups and bridge bonds. Under milder conditions, the Friedel-Crafts alkylation reaction can open the strong hydrogen bonds between aromatic nuclei to weaken the intermolecular forces and cause little structural damage. Ultrafine coal powder, as rigid particles blended with polymers, can significantly improve the mechanical strength and thermal deformation temperature of linear polymer materials, reduce the shrinkage rate, warpage deformation and cost of composite materials. This is an important step in rubber production and processing technology. A very important aspect. Since the strength of styrene-butadiene rubber is still very low after vulcanization, using carbon black as a filler can greatly improve the strength of styrene-butadiene rubber.

The coal particles are dispersed evenly on the tensile section of the alkylation-modified coal sample composite material, and the styrene-butadiene rubber composite material has achieved good modification effects. When a composite material is filled with a high content of carbon black, its tensile fracture is brittle fracture. Compared with carbon black, ultrafine coal powder has larger particle size than carbon black particles and is more easily dispersed evenly in the polymer, making it less likely to form bridging phenomena; a small amount of carbon black particles exist in the form of sub-micron aggregates. When subjected to external forces, a large number of shear bands will be generated and a large amount of energy will be absorbed, thereby greatly improving the toughness of the composite material.

Styrene-butadiene rubber application outlook

In recent years, the world economy has been weak and rubber demand has grown slowly. On the one hand, new natural rubber resources have grown rapidly, natural rubber inventories have increased, and prices have fallen, which has continued to suppress the price of synthetic rubber. On the other hand, in the next two years, my country’s new synthetic rubber production capacity will continue to be released, and the surplus will further increase. In the future, our country must control investment in synthetic rubber equipment to avoid further overcapacity, especially for styrene-butadiene rubber, which has an obvious excess. At the same time, it is necessary to strengthen product brand research, pay attention to production technology research, and develop high-performance synthetic rubber, such as SSBR, rare earth butadiene rubber, bromobutyl rubber, hydrogenated nitrile rubber, etc. It is necessary to develop thermoplastic rubber products that have both rubber and plastic properties, and improve rubber properties and reduce production costs by introducing third monomers.

References

[1] Lu Jianjun, Zhao Yansheng, Bao Weiren, et al. Ultrafine coal powder filled polymer insulation materials [J]. Journal of Coal Science, 2005(2):229- 232.

【2】Gao Yuekai. Structural performance analysis and physical properties molecular simulation study of styrene-butadiene rubber [D]. Beijing: Beijing University of Chemical Technology, 2013.

【3】 Bai Shulin, Chen Jiankang, Wang Jianxiang. Progress in experimental research on interface mechanical behavior of blended/filled polymer composites [J]. Progress in Mechanics, 2006(4):507-516.

[4] China Synthetic Rubber Industry Overview[M]. China Metrology Press, edited by China Synthetic Rubber Industry Association, 2005