Synthetic Rubber

Synthetic rubber exists for two principle reasons: the chemical deficiencies of latex rubber and the Second World War. Natural latex rubber is chemically unstable. It consists of large numbers of long chain hydrocarbon molecules bundled together. This makes it physically very weak with poor tear resistance and a tendancy to soften as the temperature rises. It can also be chemically attacked by just about anything. Many of these problems can be reduced by vulcanisation. This caused the long chain molecules to cross-link. Consequently, vulcanised latex rubber is stronger, more elastic, and less vulnerable to chemical attack. However, it is still an extremely vulnerable material. The need to replace latex rubber with an even more stable elastic material was very high. However, making synthetic rubber was easier said than done.

$Rubber rapture home page button image.$ $Spacer image.$ $View cart button image.$ $Spacer image.$ $Check out page button image.$

Synthetic rubber history is quite complex. The Second World War also created a need for a replacement to latex rubber for the simple reason of Japanese military expansion. Many of the world's prime sources of latex rubber were captured by the Japanese early in the Second World War. This left the western allies in desperate need of a viable alternative. Probably the most important war time synthetic rubbers were thiokol rubber, neoprene rubber, polyurethane rubber and silicone rubber. Since WWII, the range of synthetic rubbers and their uses have continued to expand. Today, they are used for everything from breast implants to rocket fuel.

Having said that, synthetic rubbers are not actually rubber. Natural latex rubber has never actually been duplicated. Synthetic rubbers are more accurately called elastomers. These are elastic materials which mimic many of the chemical and physical properties of latex rubber, but differ significantly in structure. One of the earliest attempts to create synthetic rubber failed, but did give silly putty to the world! Aside from a few natural product impurities, natural rubber is essentially a polymer of isoprene units, a hydrocarbon diene monomer. Synthetic rubber can be made as a polymer of isoprene or various other monomers.

Synthetic rubber is an artificial polymer material which acts as an elastomer. An elastomer is a material that can undergo elastic deformation under stress and still return to its previous size and shape without permanent deformation. Synthetic rubber serves as a substitute for natural latex rubber in many cases, especially when improved material properties are needed.

Natural rubber is derived from certain types of plant latex and consists mostly of polymerized isoprene with a small percentage of impurities. This limits the range of properties available to it, although the addition of sulphur and vulcanisation are used to improve the properties of natural latex rubber. However, synthetic rubber can be made from the polymerization of a variety of monomers including isoprene (2-methyl-1,3-butadiene), 1,3-butadiene, chloroprene (2-chloro-1,3-butadiene), and isobutylene (methylpropene) with a small percentage of isoprene for cross-linking. Furthermore, these and other monomers can be mixed in various desirable proportions to be copolymerised for a wide range of physical, mechanical, and chemical properties. The monomers can be produced pure and addition of impurities or additives can be controlled by design to give optimal properties. Polymerization of pure monomers can be better controlled to give a desired proportion of cis and trans double bonds.

Early Synthetic Rubber
In 1826 Michael Faraday showed that the composition of rubber corresponded to the formula (C5H8)n; and in 1860 Greville Williams, another English chemist, decomposed rubber by heat and isolated a chemical substance called isoprene, having the formula C5H8. In 1879, the French chemist Bouchardat succeeded in changing isoprene into a rubberlike material, one of the first synthetic rubbers produced. However, Sir William A. Tilden in England was the first to prepare a rubberlike material from isoprene, which he synthesized from turpentine. From 1908 to 1910, Hoffman and Harries in Germany and Mathews and Strange in England carried out intensive studies on the polymerization of butadiene, isoprene, and dimethylbuta diene. They discovered the method of preparing synthetic rubbers by polymerizing these hydrocarbons with sodium, a process which was later used commercially by Germany during World War I.

Thiokol Rubber
In 1920, while attempting to prepare a new antifreeze from ethylene dichloride and sodium polysulfide, J. C. Patrick discovered instead a new rubberlike substance that he termed Thiokol.It was not until 1930, however, that Thiokol was produced commercially. Thiokol has excellent resistance to gasoline and aromatic solvents. It ages well and has good tear resistance and low permeability to gases. Though not a true synthetic rubber, it nevertheless finds wide use as a specialty rubber.

Thiokol is classified as a synthetic polysulfide polymer rubber. The name Thiokol is derived from the greek words for sulfur (theio) and glue (kolla). This synthetic rubber essentially consists of long chain, hydrocarbon polymer molecules, cross linked with sulphur molecules to provide strength and chemical stability. The use of sulphur to stabilise natural latex rubber became popular through the accidental discovery of vulcanisation by Charles Goodyear in 1839.

The most well known advocate of thiokol rubber was The Thiokol Chemical Company, founded in 1929. Initially, this company's prime business was synthetic rubber sealants. However, scientists at the Jet Propulsion Laboratory found that thiokol rubber made an affective rocket fuel. Thiokol quickly embraced the new product line. Its rocket motors powered some of the most famous rockets and missiles of all time. However, Thiokol is most notorious for the Space Shuttle solid booster O-ring failure. When used in solid rocket propellant, synthetic rubbers are employed as binders. These binders double as a fuel source while suspending oxidizers and other additives in place. Synthetic rubber binders allow complex combustion chamber shapes to be formed within the propellant. The most common of these is the burning star. Thiokol rubber was used for many years in the sergeant and falcon missiles.

Neoprene Rubber
A rubberlike polymer, or elastomer, known as neoprene, based on the researches of J. A. Nieuwland of the University of Notre Dame, was announced by the DuPont Company in 1931. Neoprene is manufactured from acetylene, which, in turn, is made from coal, limestone and water. The acetylene is first polymerized to vinyl-acetylene, to which hydrochloric acid is added to produce chloroprene. Chloroprene is then polymerized to neoprene. In addition to being oil-resistant, neoprene has good heat and chemical resistance and is used in the manufacture of hose, tubing, gloves, and mechanical parts such as gears, gaskets, and belting. During World War II, neoprene was manufactured under the government-sponsored synthetic-rubber program and was designated as GR-M.

Neoprene is the trade name for a family of synthetic rubbers based on polychloroprene (The scientific name for neoprene rubber is polychloroprene). This synthetic rubber is made by polymerising the compound 2-chlorobuta-1,2-diene. Neoprene was invented in 1930 by scientists working for the DuPont company and was the first successful synthetic rubber made.

Today, neoprene rubber is considered to be rather old fashioned. However, it is still found in a wide range of products including tyres, noise isolation mountings and as the base for adhesives. Neoprene is often used in place of natural latex rubber in applications requiring resistance to chemical attack. The use of neoprene in the construction of rubber clothing is largely limited to wet suits. Some protective rubber clothing is made from neoprene, but this role is still largely occupied by latex rubber.

Polychloroprene is an organic compound, composed of carbon and hydrogen atoms. And it is a polymer formed by linking together many smaller molecules known as monomers. In this case, the monomers are chloroprene, C4H5Cl. This process is achieved through vulcanisation.

Buna S (SBR - Buna Synthetic Rubber)
In 1935, Germany announced the commercial product Buna synthetic rubber. The word ``Buna'' is derived from the first two letters of the words ``butadiene'' and ``natrium.'' Butadiene is the main chemical raw material, and sodium (natrium) was used as the catalyst in the polymerization. Two types of Buna rubbers, Buna S and Buna N, were produced in Germany. Buna S, a copolymer of butadiene and styrene, was used as a general-purpose rubber for tires and tubes.

Polyurethane Rubber
A class of elastomers known as polyurethanes is finding application as foams, adhesives, coatings, and molded goods. The manufacture of polyurethanes involves several distinct steps. A polyester is first produced from the reaction of a dicarboxylic acid, such as adipic acid, and a polyhydric alcohol, such as ethylene glycol or diethylene glycol. The polyester is treated with a diisocyanate, such as tolylene-2,4-diisocyanate or methylene diphenylene diisocyanate. The product of this reaction is treated with water and a suitable catalyst, such as N-ethyl-morpholine, to yield a resilient or flexible polyurethane foam. With additional diisocyanate, molded articles, such as tires, are produced. By varying the glycol and the dicarboxylic acid in the polyester preparation, it is possible to produce polyurethanes which can be used as adhesives or which can be fabricated into rigid foams, flexible foams, or molded articles. Polyurethane foams are flame resistant, have high tensile strength, and excellent tear and abrasion resistances. They have exceptionally high load-bearing capacities and age well. Vulcanized polyurethane rubbers have high tensile strength, excellent abrasion and tear resistances, and good oil resistance; they age well. A polyurethane rubber obtained from a polyether instead of a polyester has been developed. It has both good low-temperature and good aging properties.

Polyurethane rubber was found to be a particularly powerful fuel, and was employed in the Polaris missile used by the US and Royal Navies. However, the low viscosity of polyurethane rocket propellant has resulted in no other major missile applications. Other roles include the FC1 female condom.

Silicone Rubber
The silicone rubbers are unsurpassed in their serviceability over a wide temperature range, from -100 degrees F (-73 degrees C) to 600 degrees F (315 degrees C.). Tensile strengths of nearly 2,000 pounds per square inch (140 kg/sq cm) have been obtained in vulcanized silicone stocks. Their aging and electrical properties are also very good. Ladenburg synthesised the first silicone rubber in 1872 by reacting diethoxydiethysilane with water and trace amounts of acids.

Rubber is one of the most useful substances known to man. Natural latex rubber has been used for thousands of years. One of the earliest known uses for latex was the construction of rubber balls by the Aztecs. These rubber balls were used in a ceremonial ball game. In the late nineteenth and early twentieth centuries, natural latex became a vital component in the industrialisation of the world economy. Latex was found in virtually everything from hosiery to steam locomotive components. However, natural latex rubber is an extremely vulnerable material. It can be attacked by everything from sunlight to human perspiration. Even the discovery of vulcanisation failed to overcome all of the short comings of latex. Synthetic rubbers have overcome many of these problems. By altering the chemical composition of synthetic rubber, it is possible to determine the physical properties of the rubber, tailoring the material for specific applications. The range of applications for synthetic rubbers is extremely diverse. These rubbers can be applied to uses ranging from breast implants, to applique armour on tanks, to the solid rocket motors of intercontinental ballistic missile (ICBM).

Rubber Tyres
Modern rubber tyres are constructed from several materials. Rubber comprises about 47 percent of the tyre, together with carbon black, steel oil, vulcanising agents and textiles. The tyre (UK spelling) or tire (US spelling) is roughly toroidal in shape and is positioned on the circumference of a wheel.

Pneumatic Rubber Tyres
Pneumatic rubber tyres are filled with air and are the principle type employed today. They essentially comprise of an elastomer material, usually rubber, reinforced with threads or wires. The air provides shock absorption by compressing when the wheel moves over a bump. The crown, or outer surface of the rubber tyre, has grooves to improve traction in poor weather. Water becomes compressed into the grooves which improves tyre to road contact.

Rubber Inner Tubes
Some rubber tyres, in particular motor bike tyres, have a fully sealed rubber tube within the tyre. This rubber inner tube contains the compressed air. The inner tubes are usually made from halobutyl rubber.

Tubeless Rubber Tyres
Other tyres use a seal between the metal wheel and the rubber tyre to contain the compressed air. Any deformation of the wheel rim will result in loss of pressure.

Reinforcing Rubber Tyres
The rubber matrix of the tyre reinforced with various threads. Rubber tyres with radial yarns are called radial yarns and are the most common type in use today. However, some cross, or bias ply tyres are still used.

Rubber Tyre Composition
Most rubber tyres actually use a mix of latex rubber and synthetic rubber. The bias of the proportions vary according to the application. Passenger car tyres usually employ about 14 percent latex rubber and 27 percent synthetic rubber. However, truck tyres usually employ about 27 percent latex rubber and 14 percent synthetic rubber. The proportion of latex rubber is even higher for aircraft tyres. Although synthetic rubbers offer many advantages over natural latex rubber in terms of mechanic properties and resistance to attack by chemicals and UV light, latex rubber is far superior in terms of controlling heat absorption and dissipation.

Recycling Rubber Tyres
The elasticity of rubber tyres is one of the main problems in attempts to recycle rubber tyres, particularly when removing the steel and textile reinforcement from the rubber matrix. In addition, removing the sulphur that is chemically combined with the rubber during vulcanisation is extremely difficult. Consequently, recycled tyre rubber is usually powdered for use as a secondary rubber where less mechanical strength is required, for example, shoe soles, rubber mats, bicycle pedals and a noise reducing additive in road surfacing.

One unusual application of recycled tyre rubber is the clothing industry. The clothes design company Scorpion exhibited a jacket made from old rubber tyres at the 2004 Skin Two Rubber Exbo, and clothes designer Bethany Shorb has produced a complete outfit from fire service rubber hose. Is rubber clothing the future for us all?

Silicone Rubber Breast Implants
Silicone gel breast implants are the most controversial of all breast implant materials, mainly due to claims of CTDs (connective tissue disorders) developing as a result of silicone rubber breast augmentation. However, it is important to note that no actual empirical evidence exists to support these claims. The fact that many women with silicone rubber implants develop CTDs is not proof of a causal link. There is no significant difference between the proportion of women with silicone rubber implants and CTDs, and the proportion of women without silicone rubber implants who also develop CTDs. The debate will no doubt continue until actual proof is determined.

First, we need to establish the difference between silicone rubber and silicon. Silicon is a naturally occurring element found in sand, quartz and rock. It's actually the second most abundant element on the earth, second only to oxygen. Silicone is made when silicon is combined with oxygen, hydrogen and carbon. Silicone can be made with a wide range of molecular weights, enabling it to exist as oils, gels, or elastomers and rubbers.

Silicone breast implants consist of a shell containing silicone gel. The shell design has changed significantly over the years. Early shells were quite thick, giving a very unnatural feel to the breast. These were replaced with thinner shells. This gave a more natural feel, but greater risk of rupture. Today's implants use multiple thin shells. Although not as soft as single thin shell implants, they do feel more natural than thick shells and offer a similar level of rupture protection.

Rubber Bearings
Rubber bearings are the main component of modern earthquake protection systems for civil engineering. These seismic base isolation bearings typically consist of layered rubber and steel pads. These bearings are used to separate the building from the ground on which they sit. These rubber bearings allow the building to move freely on shaking ground. The rubber bearings comprise three layers. The top and bottom layers are usually steel. The middle layer is rubber.

Solid Rocket Motors
Perhaps the most surprising use of rubber is in solid propellent rocket motors. In this application rubber is used as both a fuel and a binder matrix to suspend other components such as oxidisers and additives. Rubber fuel tends to be a little smokey, which limits its use in tactical or battlefield missiles, but it is very suitable for larger applications such as ICBMs and satellite launch vehicles.

SIZE GUIDE $Spacer image.$ COLOURS OF LATEX

Readymade | Custom | Bespoke

$company number$