Butyl Rubber

The element, which is used in making the inner tubes of balls, gloves and other such elements, is butyl rubber. It is formed with the combination of isoprene and isobutylene. Another name for this rubber is IIR which means Isobutylene Isoprene Rubber. 

Its commercialization took place in 1943, making it the first rubber that was synthesized. It is used for several applications such as butyl rubber adhesive, the key reason being its gas permeability, low moisture and shock absorption. 

The first production of Butyl rubber was carried out by two American chemists, Robert Thomas and William Sparks. This took place at Standard Oil Company in New Jersey in the year 1937. 

They copolymerized isobutylene with isoprene present in less than 2%. Earlier, Butyl Rubber was called ‘Futile Butyl’. During the time of world war-2, this was called GR-2. It stood for Government Rubber-Isobutylene. 

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Production of Butyl Rubber

The production of both isoprene and isobutylene is carried out through thermal cracking of the natural gas. Or it is even done through lighter fractions of the gas oil. Under normal temperature and pressure conditions, physically, isobutylene is obtained in a gaseous form while isoprene occurs as a volatile liquid. 

To convert isobutylene into butyl rubber, it is stored under very low temperatures and is further diluted with methyl chloride. Following this, the addition of isoprene is done in the presence of aluminium chloride. This initiates the reaction leading to copolymerization of these elements. This makes isoprene gain good strength, just like natural rubber. 

Further, the presence of unsaturated groups makes it resistant to oxidation. In the case of temperature above glass transition, butyl rubber exhibits an unusually slow molecular motion rate. 

Fundamentals of Butyl Rubber

The following points can help you understand the structure and properties of Butyl rubber:

• It is a vinyl elastomer. It has a similar structure to polypropylene and polyethylene. 

• The process of its formation is called cationic vinyl polymerization and is formed from the monomer of isobutylene.

• The reaction is usually carried out under low temperatures, the reason being that its process is very fast. 

• The double bonds are created through the addition of isoprene making it crosslinked through vulcanization, and further exhibiting a nature similar to natural rubber. 

• With the development of its halogenated, chlorinated and brominated forms, the curing rates were improved in the 1960s. 

• Charles Goodyear did the invention of the process of vulcanization in 1839. It is a process for thermosetting, which allows vulcanization after product formation. 

Advantages of Butyl Rubber

Among all elastomers, Butyl rubber is the only one known which is impervious to gases. The various advantages of butyl rubber are as follows:

• Flexibility in the material

• Butyl rubber is biocompatible. This makes it resistant to alkaline and acidic chemicals, weathering and it has good ageing properties. 

• The performance of Butyl rubber is reduced in the presence of petroleum-based fluids, minerals, hydrocarbons, and others. 

• It offers good insulation.

• The usability temperature of the Butyl rubber is between -50 to 250℉. However, at even higher temperatures, its damping characteristics start diminishing. 

The Various Mechanical Strengths and Weaknesses of Butyl Rubber are Listed below:

• A fair compression set

• It has a very bad rebound rating

• It offers excellent flex cracking resistance

• It has good abrasion resistance

• The tear resistance is good

• It has excellent resistance towards weather and sunlight

• It has poor resistance to flame

• The oxidation, water, steam and ozone resistance are excellent

Applications of Butyl Rubber

The various applications that Butyl rubber is used for are as follows:

• The Butyl rubber tube can be formed through this easily. The key reason for this is low gas and vapour permeability. Alongside, it is also used to manufacture inner tubes, gloves, ball bladders, etc. 

• After combining with other elements, the liquid butyl rubber leads to the formation of polyisobutylene, which makes oil and other additives of fuel for machining lubricants. 

• It also serves the use as a sealant to insulate the windows. 

• The Butyl rubber strip is used for car and truck body mounts, suspension bushings, and others. 

• The stoppers utilized in labs and equipment are also made of this material. 

• The Butyl rubber sheet is also used for making gas masks, considering its low permeability. 

• It is also available in the form of Butyl rubber adhesive. 

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