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Material Types

Material Types available from Martin’s

Neoprene

Chloroprene (Developed by DuPont as Neoprene®) was one of the earliest commercially available synthetic rubber material types, and provides a good all round performance at reasonable cost. It is available in commercial and specification grades, both as mouding compound and finished sheeted forms, and has a wide variety of general engineering applications given its good performance with resistance to fuel splash, weathering and mechanical damage.

Nitrile

Another of the early synthetic rubber material types based on oil, Nitrile was a result of the search for elastomers that would withstand lubricating oil and fuels, to allow the design of better sealing systems as technology advanced in the 1930’s. Sometimes known as Buna-N or Perbunan, it has good all round performance with oils and fuels, and its typically used in applications such as rubber O rings and gaskets because of this. There are more modern materials available now for enhanced performance and resistance to modern fuels, however Nitrile remains a very common and appropriate solution.

EPDM

A synthetic rubber with very inert chemical properties which gives it great weathering resistance and good all round performance other than contact with fuels and oils. Widely used as a lower cost polymer, with good processing abilities, however the very inert nature of the manterial also means it is difficult to adhere to, and this can be a limitation. Many applications where external weathering will occur, such as construction and architectural glazing installations.

Silicone

A synthetic rubber with exceptionally wide temperature range, from low to high. It has excellent cosmetic and weathering properties and the clear nature of the gum stock means it can be accurately coloured, and unlike other polymers where carbon black increases the strength of the rubber, the strength is not adversely affected by the chioce of colour. Silicone is generally not a particularly high strength material and does tear relatively easily, although we have special compound grades with much better tear resistance than “standard” silicones. It is also generally a low toxic material, and with special compounding, often used in medical applications.

Fluorosilicone

Similar in properties to Silicone rubber, having exceptional temperature range and good cosmetics, but with enhanced resistance to oils and fuels. As such it is not a particularly strong polymer, and is extremely expensive, so care should be taken to ensure that it is the most suitable material for any given application.

Natural

The original “Gutta Percha” derived from the sap of the Rubber Tree in South America and brough back to Europe as a curiosity by the early explorers. Commercialisation started in the mid 19th century with Mackintosh and Dunlop et al, and Victorian engineers began to prize its unique properties. It is a wholly “green” material naturally produced and biodegradeable, and in its high quality forms, to this day is one of the most resilient materials in the entire polymer family, with most road tyres still having a tread made of high grade natural rubber.

Vamac®

A recent addition to the synthetic family producced by DuPont® with excellent toughness, oil and weathering resistance, with typical applications being high volume automotive gaiters and driveshaft boots.

Epichlorhydrin

Another relatively recent synthetic, featuring good oil and weathering resistance, a high temperature limit of 150°c which exceds Nitrile and a low temperature limit of -40°c which also exceeds Nitrile, however it is somewhat weaker than Nitrile and is substantially more expensive.

HNBR

A very good synthetic having good moulding characteristics, better physical properties than Nitrile and excellent thermal and abraision resistance, and good hot water and steam performance. It is relatively expensive, but finds applications in automotive drive trains, timing belts, cam chain tensioners etc., and has excellent resistance to explosive decompression, which makes it ideal for many downhole oil & gas applications.

SBR

A low cost synthetic rubber which is easily processed, with good physical and colouring properties. It does not have great resistance to oils & fuels or weathering, but has applications such as footwear and is often blended into other polymers.

Fluoroelastomer

Often known as Viton® it is thought of as a super elastomer, however whilst it has excellent temperature and chemical resistance, it is relatively weak, does not perform well at low temperatures and is attacked by steam. Noneltheless this expensive family of polymers is very useful and a variety of alternative versions exist with a combination of properties, although some of the more extreme versions are quite difficult to process.

Aflas®

A recent synthetic rubber with exceptional high temperature performance, surviving 230°c continuous service, with superior chemical, oil and fuel resistance, and unlike fluoroelastomer, good steam resistance. Often used in Oil & Gas applications where extreme perfomance is required, but, an expensive option.

Perfluoroelastomer

The most chemically resistant elastomer available, with temperature performance up to 370°c and resistance to almost every known chemical, it is virtually a rubber like PTFE. It is expensive and tricky to process, but for that particularly extreme or performance critical application, the material of choice.

Butyl

An early synthetic rubber which exhibits particularly good weathering and gas permeability performance, and as such is used extensively for gas tight seal. It has reasonable physical properties although it does not resist oils and fuels well. It finds wide application in tyre inner tubes, NBC protection and roofing or pond lining materials.

PVC/Nitrile

A blend of PVC and Nitrile, this synthetic rubber has good wear and weather resistance, processability, oil and fuel resistance and good cosmetic and colouring properties.

Cyanoacrylate

An acrylic resin adhesive developed in the 1940’s which rapidly polymerises when exposed to water, forming very strong bonds across a wide range of rubbers and substrates, although its shear strength is not particularly high. The cured adhesive is rigid and when used to bond rubber to itself can result in a noticeable hard point at the joint.

Epoxy Resin

An adhesive or potting material made of a resin and hardener which when mixed, cure to form a copolymer, often thermosetting to a final state. The mix ratio and various reinforcing additives can give a wide variety properties, and these systems are particularly useful for bonding rubber to solid substrates.

Contact Adhesive

An adhesive consisting of a material suspended in a solvent carrier, which, once applied to a substrate and the solvent having been allowed to evolve, leaves a tacky layer of adhesive material which, when mated with a similar layer of adhesive, forms a bond on contact. Many types of solvent and adhesive systems exist, but all rely on accurate placement of the mating parts first time.

Polyurethane

A range of elastomers which are copolymers of Polyol and Isocyanate, which when mixed form a cured solid or foam material, also available as a millable thermoset moulding compound. They feature very good abraision and tear resistance, hardness form very soft to very hard depending on the mix ratios and systems involved, and can have additives to confer enhanced flammability resistance, ozone protection etc.

Cork

This traditional yet exceptionally useful gasket material is a matrix of cork granules held in a rubber binder. The excellent compression set and resilience of cork, coupled with the stability of a rubber binder creates a range of economical but very useful materials. Various grades of cork and rubber are combined to provide a vriety of chemical and physical properties suitable for many gasket applications, common trade names being Nebar® and Tico®

Copper

When used in thin sections, annealed copper is a useful gasket or shim  material, often in high pressure applications.

Acetal

Also known as POM or Delrin®, this tough engineering plastic features high abraision and heat resistance, low friction and water absorbtion (unlike Nylon) and good electrical insulation along with good dimensional stability.

PTFE

Also known as Teflon (R) this engineering plastic was invented in the 1940’s and is a solid fluorocarbon featuring an exceptionally low coefficient of friction and extreme chemical resistance. It can creep under excessive temperature and pressure, but reinforcing ingredients can confer a wide range of additional properties depending on the application on question.

PEEK®

An exceptionally high performance engineering plastic featuring high temperature stability, toughness and suitability for high vacuum applications.

Torlon®

An exceptionally high performance engineering plastic featuring high temperature stability, toughness and chemical resistance.

Tufnol®

A range of phenolic resins with various types of fabric materials inserted to provide strength and stability. As engineering plastics they are available in sheet or plate form, and can be machined or punched to shape, providing robust products with good temperature and electrical insuation properties.

Melinex & Mylar®

Polyester film products typically supplied in gasket or shim form.

Plastazote®

A crosslinked closed cell polyethylene foam in a variety of densities and colours, with improved temperature resistance, stiffness and inert properties. Mainly used for packaging and protective padding purposes.

Evazote®

A crosslinked closed cell ethylene foam that is tougher and more resilient than Plastazote.