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Synthetic rubber
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Product description
Rubber is a collective term for macromolecular substances of natural (natural rubber - NR) or synthetic origin (synthetic rubber - SR).
There were a number of reasons responsible for the development of an alternative or substitute for natural rubber. These included volatile or rising prices for natural rubber on the world market in response to the general state of the economy, political events which cut customers off from the suppliers of raw materials, long transport distances, regional constraints with respect to establishing rubber plantations and the increase in global demand for rubber.
Synthetic rubber is a white, crumbly, plastic mass which can be processed and vulcanized in the same way as natural rubber.
Synthetic rubber is produced in different ways. Figure 1 illustrates one of the common production processes.
Figure 1: Production process for synthetic rubber
Synthetic rubbers are artificially produced materials with properties similar to natural rubber. Most are obtained by polymerization or polycondensation of unsaturated monomers. A wide range of different synthetic rubbers have emerged, reflecting the various different applications and the chemical and mechanical properties they require. Co-polymerization of different monomers allows the material properties to be varied across a wide range.
Polymerization can take place under hot or cold conditions, which result in hot polymers (hot rubber) or cold polymers (cold rubber).
Synthetic rubbers are marketed as compressed bales and square blocks. They are also produced in the form of powder rubber, talcum-coated chips, granules and as latex concentrates in liquid form.
Quality/Duration of storage
The benefits compared with natural rubber include better oil and temperature resistance and the possibility of a product with an extremely constant quality. Synthetic rubbers made from butadiene (polybutadiene copolymers) rank as the most important synthetic rubbers produced.
The following list indicates some of the most important synthetic rubbers along with their properties in comparison with natural rubber.
Styrene butadiene rubber (SBR)
General purpose rubber made up of different types; better abrasion resistance, lower elasticity, poorer low-temperature behavior, better heat and aging resistance, excellent electrical insulation material similar to rubber
Polybutadiene rubber (BR)
Poor processing properties mean that BR is not used on its own, blended with SBR or NR, abrasion-resistant, good elasticity, flexible at low temperatures.
Isoprene rubber (IR)
Properties largely comparable with natural rubber, more uniform, cleaner, transparent.
Acrylonitrile butadiene rubber (NBR)
Oil and fuel resistant, good heat distortion temperature properties, abrasion resistant.
Chloroprene rubber (CR)
Flame retardant, resistant to grease, oil, weathering and aging, abrasion resistant.
Butyl rubber (IIR)
Low permeability to gases, resistant to aging, ozone and chemicals, good mechanical properties, abrasion resistant, good electrical insulation properties.
The mechanical properties are improved by adding fillers such as carbon black during vulcanization with sulfur. Temperature resistance, abrasion resistance, aging resistance, resistance to oxygen and chemicals such as acids and petrol are properties which are improved in this way.
Duration of storage varies depending on the type of synthetic rubber. For example, a range of 6 - 36 months if the ideal conditions recommended by the manufacturer, such as a storage temperature between 10 and 25°C, are observed. Synthetic rubber must be stowed dry, some synthetic rubbers must be stored cool and they are to be protected from direct sunlight. [75]
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Nguồn:
http://www.tis-gdv.de/tis_e/ware/kautschuk/synthesekautschuk/synthesekautschuk.htm
