Give preparation reaction, properties and applications of Styrene-Butadiene Rubber SBR.

Styrene-butadiene rubber (SBR), a general-purpose synthetic rubber, produced from a copolymer of styrene and butadiene. Styrene-Butadiene rubber (SBR or Styrene-butadiene) is a synthetic rubber comprising of styrene and butadiene monomers. The random copolymer has characteristics like natural rubber and contains:

  • Styrene content in the range of 10-25% contributing to good wearing and bonding characteristics
  • While the butadiene unit is composed approximately 60 to 70% trans-1,4; 15 to 20% cis-1,4; and 15 to 20% 1,2 configurations for the polymer at 50°C.

Key benefits of SBR include:
  • Abrasion resistance 
  • Perfect impact strength
  • Good resilience 
  • High tensile strength

Also, when compared with polybutadiene rubber alone, styrene-butadiene rubber has improved strength, abrasion resistance, and blend compatibility. These properties are further enhanced with the use of additives.

Main applications of styrene butadiene rubber include tires and tire products, automotive parts and mechanical rubber goods.

Structure and Properties of SBR

SBR manufacturing method was first developed in Germany in 1930s when IG Farben's Walter Bock and Eduard Tschunkur polymerized a synthetic rubber called Buna-S from butadiene and styrene in an aqueous emulsion. Then the first solution polymerized random SBR grades were produced commercially by Firestone and Phillips during 1960s.

Today there are two major types of SBR with different properties based on their manufacturing process:

  • Emulsion SBR (e-SBR) - Hot SBR or Cold SBR
  • Solution SBR (s-SBR)

While most of the properties of SBR are comparable with NR, but in some respects like heat build-up, tack and gum tensile strength make it inferior to natural rubber. Other disadvantages include:

  • Low elongation at break
  • Low hot tear strength
  • Hysteresis, resilience

But the addition of resins and reinforcing fillers adequately improve these properties. However, there are properties which makes it superior over natural rubber

These include:

  • Better processability, 
  • Slightly Better heat aging 
  • Better abrasion resistance and resistance to degradation (under heat)

Also, scorch problems are less likely to occur with SBR than with NR. Overall, the most important factors in the commercial viability of SBR making it material of choice over other rubbers are:

  • Wide availability
  • Low cost compared with those of all other synthetic rubbers, 
  • Ability to accept high filler levels, 
  • Relatively stable price compared with that of NR and 
  • Overall properties on a cost/performance basis

How do you prepare SBR rubber?

A pure SBR sample was prepared by melting 2.0 g of SBR granules in 200 mL of a chloroform solution. It was then evaporated at room temperature for 24 h, followed by oven-drying with P2O5 at 40 ◦C overnight before compression molding to form a solid rubber structure.

Applications of Styrene-Butadiene Rubber SBR

Main applications of styrene butadiene rubber include tires and tire products, automotive parts and mechanical rubber goods. Styrene-butadiene rubber is the highest volume general-purpose synthetic rubber in production for a reason. It is used across a broad range of applications, spanning everything from car tyres, shoe soles and heels, drive couplings, automotive parts and mechanical rubber goods.

What is styrene-butadiene styrene used for?

Poly(styrene-butadiene-styrene), or SBS, is a hard rubber that is used for products like the soles of shoes, tire treads, and other places where durability is important. It is a type of copolymer called a block copolymer.

What is the properties of SBR?

SBR is a copolymer of styrene and butadiene and has properties similar to Natural Rubber. It has good abrasion resistance, excellent impact strength, very good resilience and a high tensile strength. The temperature range of SBR is -40˚F to +180˚F.

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