Styrene butadiene rubber categories

Styrene butadiene rubber categories

Styrene butadiene rubber emulsion method

In this method for styrene butadiene rubber , polymerization is done through free radicals, which is done in both hot and cold states. Styrene butadiene rubber obtained by cold method in the presence of oil or in the presence of oil-soot has high linearity, narrow molecular distribution, high molecular mass and difficult processing. Styrene butadiene rubber obtained by hot method is also highly branched and has a wide molecular mass distribution, good process ability and higher percentages of 1 and 2-vinyl.

Solution method

In this method is ion polymerization, Styrene butadiene rubber of this method has high linearity, high flexibility and high abrasion and tear resistance against dynamic stresses.

Gel method

The product of this method has a weak percentage of chemical bonds during the polymerization reaction between the chains, which reduces the mobility of the chains and improves processability.

Cooking method

It is mainly done by sulfur vulcanization method. The cooking speed in the Styrene butadiene rubber is slower than the NR so the accelerator is used to increase the cooking speed.

Emulsion SBR (e-SBR)

Styrene butadiene rubber can be produced by free-radical emulsion polymerization of styrene and butadiene either at 50 to 60°C (hot emulsion SBR) or at about 5°C (cold emulsion SBR). The hot emulsion Styrene butadiene rubber process, which was developed first, leads to a more branched polymer than the cold emulsion process. SBR grades produced using this process have exception processing characteristics such as low mill shrinkage, good dimensional stability, and good extrusion characteristics.
On the other hand, Cold Styrene butadiene rubber has a better abrasion resistance and, consequently, provides better tread wear and dynamic properties. It also exhibits superior mechanical properties such as tensile strength compared to grades produced by the hot emulsion polymerization route.

Key features
  • Green strength becomes low with increasing oil extension
  • Low resilience and low tensile strength
  • Outstanding resistance to abrasion
  • Low resistance to oil, other hydrocarbon fluids and ozone
  • Hot polymers are difficult to process with low green strength
  • Poor tear strength
    High styrene resins have good low-temperature properties but stiffen
Solution Styrene butadiene rubber (S-SBR)

Solution Styrene butadiene rubber  is produced by termination-free*, anionic solution polymerization of styrene and butadiene with alkyl lithium initiator (e.g., butyllithium) in a hydrocarbon solvent, usually hexane or cyclohexane. S-Styrene butadiene rubber grades have improved flexibility, performance, superior mechanical properties like tensile strength, low rolling resistance etc. especially when used in tires. Solution Styrene butadiene rubber has a narrower molecular weight distribution, higher molecular weight, and higher cis-1,4-polybutadiene content than emulsion polymerization SBR. S-Styrene butadiene rubber rarely has more than 2% non-rubber materials in its finished form while e-Styrene butadiene rubber may have an emulsifier (soap) content of up to 5% and nonrubber materials sometimes in excess of 10%.

Key features
  • Good resilience and tensile strength
  • Outstanding resistance to abrasion and fatigue
  • Low resistance to oil, other hydrocarbon fluids and ozone

*It enables the synthesis of polymers with a very narrow molecular weight distribution and less chain branching.

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