Rubber technology is the subject dealing with the transformation of rubber

Rubber

Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

s or elastomer

Elastomer

An elastomer is a polymer with the property of viscoelasticity , generally having notably low Young's modulus and high yield strain compared with other materials. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, although the latter is preferred...

s into useful products, such as automobile

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

 tire

Tire

A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...

s.The materials includes latex

Latex

Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...

, natural rubber, synthetic rubber

Synthetic rubber

Synthetic rubber is is any type of artificial elastomer, invariably a polymer. An elastomer is a material with the mechanical property that it can undergo much more elastic deformation under stress than most materials and still return to its previous size without permanent deformation...

 and other polymeric materials, such as thermoplastic elastomer

Thermoplastic elastomer

Thermoplastic elastomers , sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers which consist of materials with both thermoplastic and elastomeric properties...

s.

Vulcanization

Most rubber products are vulcanized, a process which involves heating with a small quantity of sulphur (or equivalent cross-linking agent so as to stabilise the polymer chains, over a wide range of temperature. This discovery was made by Charles Goodyear

Charles Goodyear

Charles Goodyear was an American inventor who developed a process to vulcanize rubber in 1839 -- a method that he perfected while living and working in Springfield, Massachusetts in 1844, and for which he received patent number 3633 from the United States Patent Office on June 15, 1844Although...

 in the 1844, but is a process restricted to polymer chains having a double-bond in the backbone. Such materials include natural rubber and polybutadiene

Polybutadiene

Polybutadiene is a synthetic rubber that is a polymer formed from the polymerization process of the monomer 1,3-butadiene.It has a high resistance to wear and is used especially in the manufacture of tires, which consumes about 70% of the production...

. The range of materials available is much wider however, since all polymers become elastomeric above their glass transition temperature. However, the elastomeric state is unstable because chains can slip past one another resulting in creep

Creep (deformation)

In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....

 or stress relaxation

Stress relaxation

Stress relaxation describes how polymers relieve stress under constant strain. Because they are viscoelastic, polymers behave in a nonlinear, non-Hookean fashion...

 under static or dynamic load conditions. Chemical cross links add the stability to the network that is needed for most practical applications.

Processing of Rubber

Methods for processing rubber include mastication

Mastication

Mastication or chewing is the process by which food is crushed and ground by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. During the mastication process, the food is positioned between the teeth for grinding by...

 and calendering

Calendering

Calendering is a finishing process used on cloth where fabric is folded in half and passed under rollers at high temperatures and pressures. Calendering is used on fabrics such as moire to produce its watered effect and also on cambric and some types of sateens.In preparation for calendering, the...

, both processes being essential to bring crude rubber into a state suitable for shaping the final product. The former breaks down the polymer chains, and lowers their molecular weight so that viscosity

Viscosity

Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...

 is low enough for further processing. After this has been achieved, various additions can be made to the material ready for cross-linking. Rubber may be masticated on a two-roll mill or in an internal mixer, such as a Banbury mixer

Banbury mixer

The Banbury Mixer is a brand of internal batch mixer. The "Banbury" trademark is owned by Farrel Corporation. Internal batch mixers such as the Banbury mixer are used for mixing or compounding rubber and plastics. The original design dates back to 1916. The mixer consists of two rotating spiral...

.

Rubber is first compounded with additives like sulphur, carbon black and accelerators. It is converted into a dough-like mixture which is then milled into sheets of desired thickness. Rubber may then be extruded or molded before being cured.