Rubber Material Properties

Natural Rubber (NR)

Natural rubber is the only non-synthetic rubber. It is a natural resource obtained from latex found in the sap of Hevea Brasiliensis trees. Natural rubber has the highest resilience of all rubbers and a low level of heat generation.

A special feature of natural rubber is that at high levels of stress, the rubber becomes very tough. As the natural rubber is stretched the amorphous polymers slip over each other and become aligned and partially crystalline. Strength is added in the direction of the polymer chains. This is called “Stress Crystallization” making the natural rubber very resistant to tearing.

What are the key properties of natural rubber?

Natural rubber has many qualities, these include:

• Fully biodegradable.
• Large deformation capacity - meaning that the material can be repeatedly loaded and unloaded.
• Strain induced crystallinity - added strength when deformed.
• Good tear strength.
• High resilience.
• Good flex fatigue and resistance.
• Good abrasion & cut resistance.
• Good set and creep resistance.
• Good adhesion

Drawbacks of natural rubber:

• Must be masticated - extra stage of processing

Chemical Compatibility of natural rubber

• Can be used with water and some diluted acids, alkalis, and chemicals.
• Not suitable for applications with petroleum-based oils and fuels, greases, and non-polar solvents.
• Susceptible to attack by oxygen, ozone, and UV. This effect can be minimized through the formulation of the compound.

Operating temperature range: -50 to +80°C

Applications for natural rubber

There are vast array of applications for natural rubber, these include:

• Engine mountings
• Truck tyres
• Anti-vibration mounts
• Drive Couplings
• Haul-off pads
• Isolators (earthquake pads)
• Bearings
• Springs

Latex natural rubber

High strength and elasticity make this a good material choice for thin, strong products.

Drawbacks of latex:

• Can cause allergic reactions.

Typical applications of latex:

• Adhesives
• Carpet backings
• Rubber gloves
• Condoms
• Medical devices
• Bungee cord
• Sheeting

Polyisoprene (IR)

Polyisoprene (IR) is a synthetically made rubber which is designed to replicate natural rubber. Polyisoprene has the same chemical structure as natural rubber and offers comparable material properties. However, polyisoprene has a slightly decreased tensile strength, tear strength and elasticity. Natural rubber is normally less pure than polyisoprene and may still contain latex proteins.

Shotblast rubber

Shotblast rubber is often used in construction as it is high wearing and has great abrasion resistance. It is usually made by compounding natural rubber with some cure system and protective agent. As no reinforcing filler is added to the compound, shotblast rubber has low stiffness and density.

What are the key properties of shotblast rubber?

Shotblast can offer you:

• High tensile properties
• Very high elasticity and elongation before break
• High shock absorption
• Good bonding strength
• Excellent abrasion resistance
• Available in FDA-approved grades
• Available in tan (natural) and black colour variants

Applications for shotblast rubber

The common types of applications for shotblast rubber are:

• Chute linings
• Scraper blades
• Gaskets
• Cabinet lining
• Skirting rubber

Styrene-Butadiene Rubber (SBR)

Styrene Butadiene Rubber is the most used rubber and accounts for 45% of all rubber produced. SBR is a family of copolymers made by polymerising styrene and butadiene. SBR is a relatively inexpensive and general-purpose rubber which can often be used as a good substitute for natural rubber. SBR usually has superior abrasion resistance and heat ageing properties compared to NR. However, SBR typically has less resilience and strength.

The double bond in the polymer chain makes SBR very susceptible to attack by ozone and oxygen.

What are the key properties of SBR?

The qualities of SBR are as follows:

• Lower Cost
• Comparable properties to Natural Rubber
• High tensile strength
• High resilience
• Heat resistance
• Flexible in low temperatures

Operating temperature range: -25 to +100 °C

Chemical compatibility of SBR:

• Resistant to water, organic acid, ketone, chemical, alcohol, and aldehyde.
• Not resistant to oil or fuel.
• Can be prone to weathering.
• Susceptible to ozone and oxygen attack.

Applications for SBR

Common applications for SBR are:

• Car tyres
• Shoe soles
• Drive couplings
• Haul-off pads

Ethylene Propylene Rubber (EPM & EPDM)

Ethylene Propylene Rubber (EPM) is a copolymer consisting of ethylene and propylene. The ethylene propylene polymer is chemically inert as it contains no double bonds.

Ethylene Propylene Diene Methylene (EPDM) is a terpolymer of ethylene, propylene, and diene monomers.

What is the difference between EPM and EPDM?

EPDM has an extra monomer added to its compound which allows the rubber to be vulcanised with sulphur or peroxide. EPM on the other hand can only be peroxide cured.

The ethylene propylene polymer is chemically inert as it contains no double bonds. The lack of double bonds in the chain protects the rubber from weathering, ageing and chemical attack. However, due to the lack of double bonds, EPM cannot be vulcanised with sulphur and must be peroxide cured.

EPDM is like EPM however with a small amount of a third monomer diene added to the rubber compound. The amount of this monomer added to the compound is around 2-5%. The addition of diene introduces double bonds to the side chain of the polymer, making the polymer chemically reactive. EPDM can therefore be sulphur or peroxide cured.

There are over 100 grades of EPM and EPDM available. The grades vary in the ratio of ethylene to propylene as well as the type and amount of the third monomer added, diene. The ratio of ethylene to the compound can affect the properties of the rubber material. For high elasticity applications, a compound with 50-60% ethylene should be chosen. Ethylene levels above 70% show the highest uncured strength.

What are the key properties of EPM and EPDM?

EPDM is one of the most purchased rubbers and has many qualities, these include:

• Excellent weather properties, ozone, and oxygen resistance
• Good chemical resistance, especially to alkalis, dilute acids, glycols, water, and steam
• High tensile strength
• High operating temperatures
• Good heat ageing resistance
• Good abrasion resistance
• Good tear resistance
• Can be compounded with large amounts of filler and oil to make it very economical and easy to process
• WRAS accredited, food grades and pharmaceutical grades are available

Drawback of EPDM and EPM:

• Can be difficult to bond
• High cost compared to other rubbers
• Very poor resistance to oil and fuels

Operating temperatures: -45 to +125°C, up to 150°C for peroxide cured EPDM.

Chemical compatibility of EPDM and EPM:

• Excellent weathering properties
• Excellent heat resistance
• Excellent ozone resistance
• Excellent chemical resistance
• Not suitable for exposure to petroleum-based fluids and di-ester lubricants.

Applications of EPM and EPDM

EPM/EPDM rubber has many different uses, and these include:

• Rubber roofing
• Electrical cables
• Car Radiator Hoses
• Long-life outdoor applications
• Water industry (WRAS accredited form)
• Good low-temperature flexibility
• Wire and cable insulation
• Automotive seals and channelling
• Gaskets and seals for dishwashers, dryers, washing machines etc.

Butyl Rubber (IIR)

Butyl Rubber (isobutylene-isoprene) is a synthetic rubber which was developed in the 1940’s. Butyl rubber demonstrates similar weather and ageing properties as EPM and EPDM as there are only a few double bonds in its main molecular chain which can be attacked.

Butyl rubber has one of the lowest permeabilities to gas of all rubber. This makes it excellent for using inner tubes for tyres and high-pressure/vacuum sealing applications. IIR also has a low resilience and is often used in high-energy absorbing applications.

What are the key properties of Butyl rubber?

The key properties of Butyl rubber are:

• Low gas permeability
• Very low resilience
• Excellent weathering resistance

Drawbacks of Butyl rubber:

• Cannot be blended with or joined well to NR or SBR

Operating temperatures: -50 to +100°C

Chemical compatibility of Butyl rubber:

• Excellent resistance to heat, ozone, and weathering
• Resistance to dilute acids and alkalis
• Not suitable for use in mineral or petroleum-based fluids

Applications for Butyl rubber

Butyl rubber can be used for:

• Reservoir linings
• Inner tubes
• Shock and vibration damping
• Diaphragms
• Gaskets
• O-rings
• Seals
• Speaker surrounds
• Bottle Closures

Neoprene - Polychloroprene (CR)

Polychloroprene Rubber (CR), commonly referred to as Neoprene, was one of the first oil-resistant rubbers to be developed. Neoprene is a chlorinated elastomer that has a similar structure to butadiene rubber but with one chlorine atom rather than hydrogen in the monomer. The chlorine atoms modify the behaviour of the rubber by making it less bouncy and less reactive. This gives CR relatively good weathering and heat resistance, especially for a polymer which contains double bonds in its chains. The chlorine also gives the material a level of fire protection making it a good material choice for cables. Neoprene offers a degree of stress crystallisation and is reasonably strong even without reinforcing filler.

What are the key properties of Neoprene rubber?

Neoprene has many qualities such as:

• Good bonding strength
• Good heat resilience (better than NR, IR, SBR and PU)
• High resilience and recovery
• Good wear resistance
• High strength in unfilled and Carbon Black filled compounds
• Moderate low temperature
• Self-extinguishing
• Relatively low cost
• Available in food quality grades

Grades Neoprene rubber is available in:

• General purpose grades (M & XD) - These grades offer the best tensile, tear strength, compression resistance, optimum heat resistance, best low-temperature properties.
• Sulphur modified grades (S) - best elasticity, best dynamic behaviour, best adhesion to metal/textile.

Drawback of Neoprene rubber:

• Cannot be vulcanised by sulphur
• Low level of physical properties

Operating temperature: -35 to +100°C

Chemical compatibility of Neoprene rubber:

• Moderate chemical and oil resistance
• Good resistance to alcohols, glycol, salts, vegetable oils
• Not compatible with carbon tetrachloride, acetone, benzene, carbon disulphide, turpentine or aromatic solvents.
• Weather resistant

Applications for Neoprene rubber

Neoprene can be used for many purposes and these include:

• Adhesives
• V-belts, conveyor belts
• Wire and cable jacketing
• Footwear and coated fabrics
• Wet suits
• Inflatables, dinghies
• Tarpaulins
• Hoses
• Mounting and bearing pads
• Windscreen wiper blades

What is Neoprene sheet?

Black neoprene (10% content) / SBR rubber 70 shore. It is used where a cheaper quality material will suit simple applications such as packing pieces, dust seals, protection pads etc. Where the material is not coming under any duress and slight resistance is required. This product is fully CE, PAH, ROHS, and REACH compliant. Seals, hoses and gaskets are made from neoprene rubber sheeting and are often used with refrigerants and oils, both animal and vegetable. Neoprene rubber sheeting is also used to provide noise isolation in power transformers and as a base for adhesives. Its resistance to burning has led to it being used as weather stripping for fire doors.

Available Finishes: 'SS' has a smooth finish on both sides, 'CC' has a cloth-print finish on both sides and 'CS' has a smooth finish on one side and a cloth-print finish on the other.

Neoprene sheet is resistent to:

• Moderate chemicals
• Acids
• Fats
• Greases
• Oils
• Good ozone
• Oxygen
• UV

Neoprene is a very hardy material. However, the presence of strong oxidizing acids and esters will cause degradation. Ketones and chlorinated, aromatic and nitro hydrocarbons are also not suitable for use with neoprene rubber.

Neoprene sheet specification

Polymer content: 10%
Density: 1.45sg
Hardness: 70 shore a
Tensile strength: 40 kg/cm2
Elongation at break: - 200%
Min temperature: -30°C
Max temperature: +90°C

Nitrile rubber

Acrylonitrile Butadiene Rubber (NBR) was the first oil-resistant synthetic rubber developed in Germany, in 1941. It was historically referred to as “Buna N” and is often simply referred to as Nitrile rubber. Nitrile is the standard rubber used in situations where oil resistance is needed.

Nitrile is a copolymer of butadiene and acrylonitrile. The butadiene component provides the elasticity of rubber. The properties of Nitrile mainly depend on the amount of acrylonitrile in the rubber compound. High amounts of acrylonitrile result in a rubber with better oil resistance. Compounds with low acrylonitrile content have a better low temperature flexibility and resilience.

The grade descriptions of Nitrile depend on the percentage of acrylonitrile present in the rubber. Rubbers with higher acrylonitrile content have greater oil and fuel resistance, tensile strength, hardness, abrasion, gas impermeability and heat resistance. High acrylonitrile content can also lead to low-temperature flexibility, resilience, and plasticiser compatibility.

What are the key properties of Nitrile rubber?

Nitrile can meet customer expectations with properties such as:

• Good bonding strength
• Excellent resistance to hydrocarbon oils, fuels, and greases
• Very good heat resistance in the absence of air
• Good hot air resistance (long term 90 °C, 40 days at 120 °C, 3 days at 150 °C)
• Very low gas permeability
• Low permanent set (needed for good sealing)
• Moderate low temperature flexibility (depending on the amount of acrylonitrile)
• Moderate tear and tensile properties
• Available in food grades, WRAS accredited grades and pharmaceutical grades

Drawbacks of Nitrile rubber:

• Requires protective agents for good oxygen and UV resistance.
• Inherently poor ozone resistance (difficult to protect against).
• Plasticiser selection is critical to avoid loss or extraction from heat and fluids. Causes shrinkage and embrittlement in seals and hose linings.

Operating temperature: -25 to +100 °C

• Low acrylonitrile materials can operate down to - 50°C
• Peroxide-cured materials can be used at temperatures up to +150°C

Chemical compatibility of Nitrile rubber:

• Excellent resistance to oils and fuels
• Good resistance to aliphatic hydrocarbons (propane, butane, petroleum oil, mineral oil and grease, diesel fuel, fuel oils)
• Good resistance to vegetable and mineral oils and greases
• Good resistance to many dilute acids, alkalis, salt solutions at low temperatures
• Good water resistance
• Not well suited for ozone or weather resistance
• Not compatible with fuel of high aromatic content, toluene, benzene, chlorinated hydrocarbons, hydrogen sulphide.
• Not compatible with polar solvents (ketone, acetone, acetic acid, esters)
• Incompatible with Strong acids
• Incompatible with Glycol based fluids

What is Nitrile sheet?

Black nitrile (10% content) / SBR rubber 70 shore. It is used where a cheaper quality material will suit in simple applications such as packing pieces, dust seals, protection pads etc where the material is not coming under any duress and slight resistance is required. Ideal for use in products when oil resistance is required such as fuel hoses, automotive seals, gaskets, rollers and in printing and textiles, nitrile rubber is an oil-resistant synthetic rubber. This product is fully CE, PAH, ROHS and REACH compliant with excellent mechanical characteristics, black nitrile rubber sheeting is suitable for use with fuels, oils, greases and water.

Nitrile sheet specification:

• Polymer content - 10%
• Density (specific gravity) - 1.45
• Hardness (shore a) - 70
• Tensile strength (kg/cm2) - 40
• Elongation at break (%) - 200
• Min temperature - -30 °C
• Max temperature - +90°C
• Abrasion resistance (mm3) - na

Available Finishes: 'SS' has a smooth finish on both sides, 'CC' has a cloth-print finish on both sides and 'CS' has a smooth finish on one side and a cloth-print finish on the other.

We stock a majority of these strip materials at all times, so the likely lead time will be between 1 and 2 days. However, should we not hold the specific product required, we'll be able to provide it within 3-5 days. Get in touch to discuss any specific requests.

Klinger / Compressed Non-Asbestos Fibre (CNAF)

Compressed fibre (often known by the brand name Klinger) is a high-quality and dependable material commonly used for gaskets. It’s made from aramid and synthetic fibres which is bonded with Nitrile.

What are the key properties of Klinger/CNAF?

CNAF has many qualities, and these include:

• Strong resistance
  • High compression
  • Chemicals
  • High temperature
  • Oil and fuels
  • Hydrocarbons
  • Water
  • Low pressure steam
• Hood mechanical strength
• WRAS approved
• Anti-stick finish
• Excellent resistance to gas leakage.
• Meets non-asbestos standard BS7531 Grade Y.

Specifications

• Temp Range - +180 deg c cont, +350% max
• Compressibility - 10% ASTM F 36 A
• Recovery - 55% astm f 36 a
• Density - 1.85 - g/cm

Applications for Klinger/CNAF

CNAF is suitable for a range of applications, these include:

• Air
• Water
• Steam
• Organic
• In-organic
• Marine
• Food and beverage
• Chemical processing

Silicone rubber (VMQ)

Silicone offers advantages over other rubber sheeting. It is a very resilient material that maintains its properties at very high and very low temperatures. They are commonly used in pharmaceutical, food and other clean industry applications. Silicone is also a great electrical insulator with excellent ozone and UV resistant capabilities. It offers high tear resistance, tensile strength and good elongation. Remaining constant whatever the temperature, silicone has excellent resistance to heat while remaining flexible at low temperatures. low in flammability, it is resistant to ultra-violet light, weathering, sea water and ozone. It is metal detectable and exhibits low smoke toxicity.

Sheet silicone is FDA-compliant 60 shore.

Silicone polymers differ from rubber as they are made with a silicon and oxygen backbone. Silicone rubbers can exhibit good elasticity over a larger temperature range than other synthetic rubbers.

Silicone rubber is inert and unlike natural rubber, does not cause any reactions within the body. This means that it is appropriate for use within the food processing industry, and it is extensively used in this environment as washers, gaskets, scrapers, curtains, and seals. Silicone is also commonly used in the automotive and medical industries.

What are the key properties of Silicone rubber?

Silicone is heavily relied upon in the food and medical industry due to it being FDA compliant not to mention the qualities it has. These include:

• Ideal for high and low temperature applications
• Excellent electrical properties
• Good resistance to weathering and ozone attack
• Excellent non adhesive properties
• Low chemical reactivity
• Low toxicity
• Flame retardant

Drawbacks of Silicone rubber:

• Physical properties are low
• Lacks strength and cannot be strengthened with Carbon Black.
• High-cost relative to other rubbers.
• Cannot be crosslinked with sulphur. Are usually cured with peroxides.

Operating temperature: -80 to +300 °C

Chemical compatibility of Silicone rubber:

• Outstanding resistance to weathering and ozone attack.
• Chemically resistant to water, alcohols, acetone, and other polar fluids.
• Not resistant to superheated steam
• Poor gas permeability
• Poor resistance to petroleum-based fluids

Applications for Silicone rubber

Silicone rubber has many different uses, these include:

• High temperature car ignition cables
• Power and control cables
• Insulated wires
• Keyboard mats
• Exhaust hangers
• Fuel valves / seals
• Aircraft window seals
• Oxygen masks and systems
• Breast pumps
• Surgical implants
• Catheters
• Cannulas
• Heart pacemakers
• Kitchen and cookware

Fluorocarbon rubber (FKM)

Fluorocarbon Rubber (FKM) is also commonly known as Viton. Fluorocarbon rubbers are a family of materials based on copolymers and terpolymers. The fluorine atoms in their molecular structure make these rubbers highly resistant to many chemicals as well as making them resistant to high temperatures. These rubbers are some of the most suitable choices for high temperature applications as they offer excellent heat resistance of up to 300°C.

What are the key properties of Fluorocarbon rubber?

Fluorocarbon rubber is a useful product with qualities such as:

• Suitable for use at very high temperatures
• Resistant to many chemicals
• More resistance to burning than non-fluorinated rubbers
• It has a working temperature ranging from -10°C to 250°C.
• It is odour free and non-toxic
• It is resistant to heat, grease, acids, oils and fuels.
• It complies with REACH and PAK requirements.
• It is FDA Approved

Drawbacks of Fluorocarbon rubber:

• Poor low temperature capabilities in the region of -10°C are generally exhibited Low temperature grades are available.

Operating Temperature: -10 to +300°C

• Can survive continuous service at ~ 205°C
• Can last for 3000 hours at 232 °C
• 1000 hours at 260 °C
• 240 hours at 288 °C
• 48 hours at 316 °C

Chemical compatibility of Fluorocarbon rubber:

• Generally wide-ranging chemical resistance
• Excellent resistance to oils, fuels, lubricants, and most mineral acids
• Unsuitable for use with phosphate esters and ketones
• Exhibit resistance to degradation by a greater variety of fluids and chemicals than any non-fluorinated elastomer

Applications for Fluorocarbon rubber

This highly reliable rubber source is useful for:

• Food processing
• Medical-based equipment and machinery
• Pharmaceutical processing
• Industrial-based matting
• Heavy-duty - gasket and extrusions

Thermoplastic elastomers (TPES)

Thermoplastic elastomers (TPE) were developed and introduced in the 1960’s. TPEs are copolymers of thermoplastics and rubber. These polymer chains are highly attracted to each other and form crosslinks as they crystallise together. These materials, therefore, behave like elastomers but have the added benefit that they do not require vulcanisation.

What are the key properties of thermoplastic elastomers?

Thermoplastic elastomers have many key qualities, these include:

• Do not need to be vulcanized
• Faster cycle times than thermoset rubber
• Elasticity in a limited range of temperatures
• Ease of recycling

Drawbacks of thermoplastic elastomers:

• Relatively high cost
• Melt at high temperatures

Operating temperatures: -40 to + 120°C

Applications for thermoplastic elastomers

Thermoplastic Elastomers are used for:

• Footwear soles
• Toys
• Leisure equipment
• Sports goods
• Automotive shock-absorbing seals
• Automotive bumper
• Vibration dampeners for automotive and construction
• Electrical insulation
• Additive for asphalting
• Medical grade equipment

Nitrile bonded cork

Black nitrile bonded cork. This is an economical and highly compressible material suitable for low and medium bolt pressure, with good flexibility and resilience. The physical characteristics along with fuel and oil resistance make this a general-purpose gasket material.

What are the key properties of nitrile bonded cork?

This reliable and cost-effective material has many qualities, these include:

• Ozone resistant
• Heat resistant (struggles in high temperatures)
• Oil and petroleum resistant
• Great for surface protection
• Bonded with Other Materials Based on Application
• Sound Suppression

Drawbacks of nitrile bonded cork:

• Not weather resistant
• Less effective in high temperatures

Operating temperature: -20°C + 120°C

Specification of nitrile bonded cork:

• Shore a - 50-70
• Cork granule size - 2/3mm
• Density - 0.6-0.7
• Compression at 400 psi 40-55%
• Recovery - 75%
• Tensile - 10.5 kg/cm2
• Flexibility - no cracks
• Volume change after immersion
• ASTM oil 1 70hrs @ 100c -10 to +10%
• ASTM oil 3 70hrs @ 100c -5 to +40%
• ASTM fuel at 22hrs at room temp -5 to +10

Applications for nitrile bonded cork:

• Anti-vibration automotive gaskets
• Anti-vibration automotive seals
• Anti-vibration automotive washers
• Water seals
• Valve covers
• Shock absorption

Insertion rubber

Insertion rubber is reinforced by layers of fabric which are “inserted” into the rubber. This internal layer of fabric is usually made of nylon or polyester and helps to increase the tensile strength and the tear resistance of the material. The fabric insert also reduces the elasticity of the plastic meaning that the material will better retain its original shape. Insertion rubbers offer similar properties to standard commercial rubber. They offer top level durability and wear resistance as they won't stretch or tear.

Insertion rubber is reliable and long lasting and is often used in extremely abrasive applications such as guards on farming machinery. Insertion rubber is often made using SBR and natural rubber with fabric inserts. For applications where oil and fuel resistance are necessary, it is recommended to use neoprene or nitrile insertion.

Insertion rubber is often cut into gaskets, washers, strips, or pads or manufactured to make sleeves. Insertion rubber sheets are available in a range of thicknesses and with varying amounts of fabric reinforcement. The number of ply refers to the number of fabric layers within the insertion rubber. For example, 5 ply insertion rubber contains 5 layers of reinforcing fabric within the material.

What are the key properties of insertion rubber?

The key properties for insertion rubber are:

• Similar properties to standard commercial rubber
• Excellent tensile strength
• Excellent tear resistance
• Low elasticity

Drawbacks of insertion rubber:

• Not suitable at temperatures over 70°
• Poor resistance against UV
• Poor resistance against oil

Specification for insertion rubber:

• Material - natural rubber / SBR
• Density (specific gravity) - 1.6
• Hardness (shore a) - 70
• Tensile strength (kg/cm2) - 30
• Elongation at break (%) - 150
• Min temperature - -20°C
• Max temperature - +70°C
• Abrasion resistance (mm3) - n/a

Applications for insertion rubber

Here are the applications for insertion rubber:

• Applications where low cost and high wear resistance are key requirements
• Guards on farming machinery
• Equestrian matting
• Gaskets
• Car boot mats
• Mud flaps
• Worktops and counters
• Horsebox and trailer partitions
• Seals
• Skirtings to prevent draughts