Materials
Materials - Polymer Families
Natural Rubber
ASTM D1418 Designation: NR
ASTM D2000, SAE J200 Type / Class: AA
STANDARD COLOR: Black
HARDNESS RANGE: 40-90 SHORE A Durometer
RELATIVE COST: Low
GENERAL TEMPERATURE RANGE: -50°C to +105°C
Natural rubber was the sole polymer before the development of synthetic elastomers in the 1930s.
Polyisoprene vulcanized from the latex of the Hevea Brasiliense trees, natural rubber was the sole polymer
before the development of synthetic elastomers back in the 1930s. Though its use has since sharply declined,
natural rubber offers many excellent characteristics, including low heat build-up, high resilience and
elongation, good abrasion resistance, and low temperature flexibility. Natural rubber has both high tensile
strength and good tear strength due to its tendency to strain crystallize. It also undergoes low compression
set. Its main drawback is its poor resistance to either oils or solvents. The double bond in its main polymer
chain also makes natural rubber susceptible to attack by oxygen, ozone, and UV light.
NR PERFORMS WELL IN:
• Alcohols
• Organic acids
• and as non-hydraulic seals
NR DOES NOT PERFORM WELL IN:
• Aromatic, aliphatic, or halogenated
• hydrocarbons
• Ozone
• Petroleum oils
Butyl Rubber
ASTM D1418 Designation: IIR
ASTM D2000, SAE J200 Type / Class: AA, BA
STANDARD COLOR: BLACK
HARDNESS RANGE: 40-90 SHORE A Durometer
TRADE NAME: Exxon Butyl® (ExxonMobil Chemicals)
Relative Cost: Medium
General Temperature Range: -50°C to +121°C
Butyl rubber offers excellent resistance to gas permeation
An unsaturated copolymer of isobutylene and isoprene, butyl rubber has two defining characteristics: It is
composed entirely of petroleum, limiting its usefulness around hydrocarbons (since “likes dissolve likes”); and
it offers excellent resistance to gas permeation, making it ideal for vacuum seals.
Though ethylene propylene (EP) is now widely used rather than butyl for a number of applications, butyl is still
used in some aircraft hydraulic systems. Butyl offers stronger resistance to sunlight and ozone than isoprene
alone; presence of the saturated isobutylene in the polymer chain makes this possible. Butyl also resists to
moderate heat, various chemicals, and mechanical abrasion.
IIR PERFORMS WELL IN:
• Hot water and steam up to 121°C
• Phosphate esters type hydraulic fluids: Skydrol®, Fyrquel®, Pydraul®
• Silicone fluids and greases
IIR DOES NOT PERFORM WELL IN:
• Mineral oil & grease
• Hydrocarbon oil & fuel
NBR Nitrile Rubber - Buna N
ASTM D1418 Designations: NBR, XNBR
ASTM D2000, SAE J200 Type / Class: BF, BG, BK, CH
STANDARD COLOR: Black
HARDNESS RANGE: 40-90 SHORE A Durometer
TRADE NAMES: Krynac® (LANXESS), Nipol® (Zeon Chemicals)
RELATIVE COST : Low / Medium
GENERAL TEMPERATURE RANGE: -40°C to +108°C
Nitrile rubber is probably the most commonly used elastomer for O-rings and other sealing devices
Nitrile rubber is probably one of the most commonly used elastomers for sealing devices. Also known as Buna
N, nitrile is a copolymer of butadiene and acrylonitrile (ACN). The name Buna N is derived from butadiene and
natrium (Latin name for sodium, the catalyst used in polymerizing butadiene). The “N” stands for acrylonitrile.
The butadiene segment imparts elasticity and low temperature flexibility. It also contains the unsaturated
double bond that is the site for crosslinking, or vulcanization. This unsaturated double bond is also the main
attack site for heat, chemicals, and oxidation. The acrylonitrile segment imparts hardness, tensile strength, and
abrasion resistance, as well as fuel and oil resistance. Heat resistance and gas impermeability are also
improved through increased ACN content, which typically ranges from 18% to 45%. A standard, general-
purpose nitrile compound usually holds 34% ACN. The relationship between the ACN content, volume swell in
ASTM # 3 oil, and the brittle point of the elastomer. General-purpose nitrile compounds with a 34% CAN
content have a recommended temperature range of -40°C to +107°C. The low temperature flexibility can be
improved by reducing the ACN content. Nitrile compounds with an ACN content of 18% to 20% are still flexible
at temperatures down to -54° C.
Compounding ingredients and polymers that offer the best low temperature properties are usually adversely
affected by high temperatures. A general-purpose compound is cured with sulfur, but as the ambient
temperature in an application exceeds +108° C, free sulfur in the compound finds other unsaturated double
bonds and forms additional crosslinks. This results in compression set and hardening of the compound. To
improve high temperature properties, a peroxide cure system and /or mineral fillers must be used. Peroxide-
cured compounds have both better high temperature properties (up to +135°C) and improved compression set
characteristics, but they are also more difficult to process and more expensive than sulfur-cured compounds.
Nitrile compounds outperform most other elastomers due to high tensile strength, as well as excellent
abrasion, tear, and compression set resistance. Nitriles also have very good aging properties under severe
conditions. Because of the double bonds present in the polybutadiene parts of the chemical backbone, nitrile
compounds have poor resistance to ozone, sunlight, and weathering. They should not be stored near ozone-
generating electric motors or equipment.
NBR PERFORMS WELL IN:
• Petroleum oils & fuels
• Silicone oils & greases NIILE – BUNA N 111
• Ethylene glycol
• Dilute acids
• Water (below 100° C)
NBR DOES NOT PERFORM WELL IN:
• Aromatic hydrocarbons (benzene, toluene, xylene)
• Automotive brake fluids
• Halogen derivatives (carbon tetrachloride, trichloroethylene)
• Ketones (MEK, acetone)
• Phosphate ester hydraulic fluids (Skydrol®, Pydraul®)
• Strong acids
Carboxylated Nitrile rubber compounds (XNBR) provide even better strength properties, especially abrasion
resistance. Carboxylated Nitriles are produced by the inclusion of carboxylic acid groups on the polymer during
polymerization. These carboxylic acid groups provide extra “pseudo” crosslinks, producing harder, tougher
compounds with higher abrasion resistance, modulus, and tensile strength than standard nitriles. Carboxylated
Nitriles are, however, less flexible at low temperatures and less resilient than non-carboxylated compounds.
Also, the “pseudo” crosslinks are thermally sensitive. As temperatures increase, the ionic bonds lose strength.
Hydrogenated Nitrile Rubber – HNBR
ASTM D1418 Designation: HNBR
ASTM D2000, SAE J200 Type / Class: DH
STANDARD COLOR: Black, Green
HARDNESS RANGE: 40-90 SHORE A Durometer
TRADE NAMES: Therban® (LANXESS), Zetpol® (Zeon Chemicals)
RELATIVE COST: Medium
GENERAL TEMPERATURE RANGE: -30° to +150° C
Hydrogenated Nitrile-Butadiene Rubber developed to provide a highly resistant new class of Nitrile rubber
As part of an ongoing effort to engineer more resistant compounds to heat, chemicals, and oxidation, a new class of nitrile was developed. Initially known as Highly Saturated Nitrile (HSN), this class is now more commonly called Hydrogenated Nitrile Butadiene Rubber (HNBR). Hydrogenated Nitrile results from the hydrogenation of standard nitrile. Hydrogenation is the process of adding hydrogen atoms to the butadiene segments. Adding hydrogen reduces the number of carbon-to-carbon double bonds that would otherwise be weak links in the polymer chain. Why are double bonds weak? It stems the ability of an atom to form one or more energy bonds with neighboring atoms. A carbon atom can form four distinct covalent bonds. Because carbon has this valence of four, it is most “satisfied” when it has actually formed four single bonds (a state known as saturation) rather than two single bonds and a double bond. A satisfied, saturated atom is more stable, so a compound composed largely of saturated carbons is less reactive and more resistant to chemical attack. HNBR’s main chain is primarily composed of highly saturated hydrocarbons and acrylonitrile (ACN). Thanks to their saturation, the hydrocarbon segments impart heat, chemical, and ozone resistance. however increased hydrogenation and heat resistance make HNBR more likely to creep. Increased hydrogenation also leads to decreased low temperature elasticity. As with standard nitrile, the ACN content of HNBR imparts toughness, as well as fuel and oil resistance. Peroxide cured HNBR has improved thermal properties and will not continue to vulcanize like sulfur-cured nitriles. Since its introduction, HNBR has proven itself in a variety of applications. Deeper and deeper oil wells require materials that can resist heat, crude oil, hydrogen sulfide (H2S), amine-based corrosion inhibitors, steam, and the detrimental effects of explosive decompression. HNBR meets these needs and is used for a variety of products, including O-rings, packings, wellhead seals, drill bit seals, blowout preventors, and drill pipe protectors. HNBR is used in automotive air conditioning systems where R134a refrigerant gas has replaced the chlorofluorocarbon (CFC)-containing R12 refrigerant. HNBR is used in fuel parts due to its increased resistance to sour gasoline and ozone. It is used in oil line parts because of its resistance to elevated temperatures, oil additives, and copper-containing metal sludge. HNBR is also finding wider use as an alternative to fluorocarbon rubber (FKM) in shaft seals. Why the switch? The hardness of the mineral fillers – primarily calcium sulfate (CaSO4) and barium sulfite (BaSO3) – used to improve fluorocarbon’s wear properties can cause grooving of the metal shaft, eventually providing a leak path that leads to seal failure. With other materials, carbon black (which is not as abrasive as the mineral fillers) might be substituted, but carbon black is not sufficient to give fluorocarbon good abrasion resistance. On the other hand, HNBR has excellent abrasion resistance, making it a viable alternative to FKM. HNBR also has better low temperature properties and tear resistance than fluorocarbon. NITRILE 107
HNBR PERFORMS WELL IN:
- Automotive applications: O-rings, timing belts, fuel injector seals, fuel hoses, shaft seals, diaphragms, and in air conditioning systems
- Oil field applications: as O-rings, well-head seals, drill-bit seals, packers, drill-pipe protectors
HNBR DOES NOT PERFORM WELL IN:
- Esters
- Ethers
- Hydrocarbons (chlorinated)
Ketones
EPM / EPDM Rubber
ASTM D1418 Designations: EPM, EPDM
ASTM D2000, SAE J200 Type / Class: AA, BA, CA, DA
STANDARD COLOR: Black
HARDNESS RANGE: 40-95 SHORE A Durometer
TRADE NAMES: Buna EP® (LANXESS), Keltan® (LANXESS), Nordel® (DuPont), Vistalon® (ExxonMobil Chemicals)
RELATIVE COST: Low
GENERAL TEMPERATURE RANGE: -55°C to +150°C
Ethylene Propylene is primarily valued for its outstanding resistance to phosphate ester type hydraulic
fluids, as well as for its wide temperature range.
Ethylene Propylene is a Copolymer of ethylene and propylene (EPM), or in some cases, a terpolymer due to the addition of a diene monomer (EPDM). This added diene monomer is important because it includes unsaturation to facilitate sulfur crosslinking.
In use since 1961, ethylene propylene is primarily valued for its outstanding resistance to Skydrol® and other phosphate ester type hydraulic fluids including Pydraul® and Fyrquel®, as well as for its typical wide temperature range. Ethylene propylene is also known for its good resistance to weathering thanks to saturation within its chemical backbone.
EPM / MEPDM PERFORMS WELL IN:
- Alcohols
- Automotive brake fluids
- Dilute acids & dilute alkalis
- Ketones (MEK, acetone)
- Silicone oils & greases
- Steam
- Water
EPM / EPDM DOES NOT PERFORM WELL IN:
- Aliphatic & aromatic hydrocarbons
- Di-ester based lubricants
- Halogenated solvents
- Petroleum oils
Silicone Rubber
ASTM D1418 Designations: MQ, PMQ, VMQ, PVMQ
ASTM D2000 / SAE J200 Type / Class: FC, FE, GE
STANDARD COLOR: Red Rust
HARDNESS RANGE: 20-80 SHORE A Durometer
TRADE NAMES: KE® (Shin-Etsu Silicones), Silastic® (Dow Corning Corp.), Silplus® (Momentive Performance Materials Inc.), Tufel® (Momentive Performance Materials Inc.)
RELATIVE COST: Medium
GENERAL TEMPERATURE RANGE: -54°C to +232°C
Silicones are primarily based on a strong sequence of silicon and oxygen atoms rather than a long chain of
carbon atoms. Silicones are the primarily “Go-to” choice for the Medical and Electronics industries.
Though carbon and hydrogen are part of their chemistry, silicones are primarily based on a strong sequence of silicon and oxygen atoms rather than a long chain of carbon atoms. This silicon-oxygen backbone is much stronger than a carbon-based backbone, making silicones more resistant to extreme temperatures, chemicals, and shearing stresses. Due to saturation in the polymer’s main chain, silicones are very resistant to oxygen, ozone, and UV light. This saturation also demands that the material be peroxide cured since it is not possible to sulfur cure a saturated polymer. In addition to being generally inert, silicones are odorless, tasteless, nontoxic, and fungus resistant. They also have great flexibility retention and low compression set.
There are four different types of silicone formulations in use today. Standard Methyl Silicone is known as MQ. By replacing a small number (typically less than 1%) of the pendent methyl (CH3) groups in MQ with vinyl (CH2CH) groups, we arrive at what is known as Vinyl Methyl Silicone, or VMQ . VMQ compounds tend to have better cure properties and undergo lower compression set than standard MQ. Replacing 5% to 10% of the methyl groups with ringed phenyl (C6H5) groups results in Phenyl Methyl Silicone, or PMQ. PMQs have better low temperature properties than MQ or VMQ. Finally, adding some of the aforementioned vinyl groups to PMQ results in Phenyl Vinyl Methyl Silicone, or PVMQ.
Silicones are not well suited for dynamic use due to their high friction characteristics, low abrasion resistance, and poor tear and tensile strength. Many silicones also suffer from above average mold shrinkage. Though they can be utilized in high aniline point oils, silicones are considered non-resistant to petroleum oils. Silicones tends to swell considerably in both aliphatic and aromatic hydrocarbon fuels unless a special compound is formulated. Silicones are also very gas permeable.
Silicones compounds allow high insulation features; however, can be modified with the addition of special conductive additives to comply with most ESD specifications and EMI / RFI shielding applications.
SILICONE PERFORMS WELL IN:
- Engine & transmission oils (mineral oils)
- Ozone
- Dry heat
SILICONE DOES NOT PERFORM WELL IN:
- Petroleum oils & fuels
- Ketones (MEK, acetone)
- Steam
- Concentrated acids
Fluorosilicone Rubber
ASTM D1418 Designation: FVMQ
ASTM D2000, SAE J200 Type / Class: FK
STANDARD COLOR: Blue
HARDNESS RANGE: 40-80 SHORE A Durometer
TRADE NAMES: FE® (Shin-Etsu Silicones), Silastic LS® (Dow Corning Corp.)
RELATIVE COST: High
GENERAL TEMPERATURE RANGE: -55°C to +180°C
Fluorosilicone compounds combine the best properties of fluorocarbons and silicones.
Fluorosilicone is the common name for fluorovinylmethyl silicone rubber. Fluorosilicones resist solvents, fuel, and oil and have high and low temperature stability. Fluorosilicones are resilient, with low compression set characteristics. Though widely used in aerospace fuel systems and auto fuel emission controls, fluorosilicones are excellent only as static seals. High friction tendencies, limited strength, and poor abrasion resistance disqualify fluorosilicones from installation at dynamic applications.
FVMQ PERFORMS WELL IN:
- Hot air
- Hydrocarbons (aromatic, chlorinated)
- Ozone
- Sunlight
FVMQ DOES NOT PERFORM WELL IN:
- Brake fluids
- Hydrazine
- Ketones
- Steam
Fluorocarbon Rubber - FKM
ASTM D1418 Designation: FKM / FPM
ASTM D2000, SAE J200 Type / Class: HK
STANDARD COLORS: Black, Brown, Green
HARDNESS RANGE: 50-90 SHORE A Durometer
TRADE NAMES: Tecnoflon® (Solvay), Viton® (DuPont), Dyneon® (3M), DAI-EL® (Daikin Industries)
RELATIVE COST: High
GENERAL TEMPERATURE RANGE: -25°C to +204°C
Fluorocarbon compounds are characterized with great “all-in-all” resistance and durability for most service environments.
They make excellent choice for sealing applications due to their exceptional resistance to chemicals, oil, petrol and temperature extremes
Also referred to as fluoroelastomers, fluorocarbon compounds are thermoset elastomers containing high level of Fluorine. Fluorocarbons make excellent choice for O-rings and seals due to their exceptional resistance to chemicals, oil, and temperature extremes. Specialty LT compounds can further extend the low temperature limits down to about -30°C for dynamic seals and about -40°C in static applications.
Fluorocarbons usually have good compression-set resistance, low gas permeability, and good resistance to ozone and sunlight. Though initially formulated for use in aerospace applications, Fluorocarbon compounds are widely used in the aviation, automotive, fluid power, medical, pharmaceutical, chemical processing and the appliance industries
Three main factors contribute to the remarkable heat and fluids resistance of fluorocarbon compounds. First, there are extremely strong bonds between the carbon atoms comprising the polymer backbone and the attached (pendant) fluorine atoms. Under most circumstances, these bonds cannot be broken, and thus the polymer is not prone to undergo chain scission – division of the macromolecular chains into smaller, weaker, more susceptible segments. Second, fluorocarbons feature a high fluorine-tohydrogen ratio. In other words, fluorine (rather than hydrogen) atoms fulfill the majority of the available bonds along the material’s carbon backbone. Polymers with a high level of fluorination have proven to be extremely stable. A stable compound is less inclined to react to, or be broken down by, its environment. Third, the carbon backbone is fully saturated. That is, it contains only single bonds between the carbon atoms. It does not contain any of the covalent double bonds present in unsaturated compounds. Since double bonds are the focus for chemical attack, the saturated structure of fluorocarbons renders them impervious to harmful agents (such as oxygen, ozone, and UV light) that typically degrade unsaturated materials.
Depending on the specific needs of your application, there are several different fluorocarbon formulations available for use. Though they may share some common characteristics, these different types are distinguished by their processing and end-use properties. Perhaps the most well-known fluorocarbon manufacturer is DuPont, to the point that the trade name for their compound, Viton®, is often used as if it were a generic term for FKM. In the interests of simplicity, the following descriptions of some of the most common FKM formulations will make use of the DuPont “type” names. The original commercial fluorocarbon, Viton A, is the general-purpose type and is still the most widely used.
Viton A is a copolymer of vinyldiene fluoride (VF2) and hexafluoropropylene (HFP). Generally composed of 66% fluorine, Viton A compounds offer excellent resistance against many automotive and aviation fuels, as well as both aliphatic and aromatic hydrocarbon process fluids and chemicals. Viton A compounds are also resistant to engine lubricating oils, aqueous fluids, steam, and mineral acids.
Viton B fluorocarbons are terpolymers combining tetrafluoroethylene (TFE) with VF2 and HFP. Depending on the exact formulation, the TFE partially replaces either the VF2 (which raises the fluorine level to approximately 68% or the HFP (keeping the fluorine level steady at 66%). Viton B compounds offer better fluids resistance than the Viton A copolymers.
Viton GF fluorocarbons are tetrapolymers composed of TFE, VF2, HFP, and small amounts of a cure site monomer. Presence of the cure site monomer allows peroxide curing of the compound, which is normally 70% fluorine. As the most fluid resistant of the various FKM types, Viton GF compounds offer improved resistance to water, steam, and acids.
Viton GFLT fluorocarbons are similar to Viton GF,except that perfluoromethylvinyl ether (PMVE) is used in place of HFP. The “LT” in Viton GFLT stands for “low FLUOROCARBON” The combination of VF2, PMVE, TFE, and a cure site monomer is designed to retain both the superior chemical resistance and high heat resistance of the G-series fluorocarbons. In addition, Viton GFLT compounds (typically 67% fluorine) offer the lowest swell and the best low temperature properties of the types discussed here Viton GFLT can seal in a static application down to approximately -40° C. A brittle point of -45° C can be achieved through careful compounding.
FLUOROCARBONS PERFORMS WELL IN:
- Acids
- Aircraft engine applications
- Gasoline (& alcohol blends)
- Hard vacuum applications
- Low outgassing applications
- Petroleum products
- Silicone fluids & greases
- Solvents
FLUOROCARBONS DOES NOT PERFORM WELL IN:
- Amines
- Hot chlorosulfonic acid
- Hot hydrofl uoric acid
- Hydrocarbons (nitro)
- Ketones
- Low molecular weight esters & ethers
- Fireproof hydraulic fl uids (e.g. Skydrol®)
Perfluoroelastomer – FFKM
ASTM D2000, SAE J200 Type / Class: KK
STANDARD COLOR: Black
HARDNESS RANGE: 60-90 SHORE A Durometer
TRADE NAMES: Kalrez® (DuPont), Tecnoflon® (Solvay), Chemraz® (GreeneTweed)
RELATIVE COST: Extremely High
GENERAL TEMPERATURE RANGE: -30°C to +325°C
Perfluorelastomers are the most advanced rubber compounds engineered for the harshest service conditions,
they are highly resilient synthetic rubbers, that retain their critical properties in chemically aggressive environments and at extreme temperatures.
O-rings, seals and gaskets made from Perfluorelastomers retain their shape, strength and flexibility at extreme temperatures. They exhibit low permeability to a broad range of fluids and chemicals, including gases, oils, lubricants, fuels, and additives. This makes them highly sought after for critical sealing applications where high purity and long service life are essential. Unlike traditional elastomers based on carbon-hydrogen or silicon-oxygen bonds, Perfluorelastomers derive their uniquely superior properties from the strength of carbon-fluorine bonds. The fully fluorinated monomers contained in the Perfluorelastomers are the reason they exhibit superior chemical and heat resistance, which make them the ultimate choice for aerospace and aviation, semiconductor, energy oil & gas, and chemical processing industries.
Most Perfluoroelastomers are terpolymers of tetrafluoroethylene (TFE), perfluoromethylvinyl ether (PMVE), and a cure site monomer (CSM). The fully fluorinated monomers contained in perfluoroelastomers allow the compounds to exhibit superior chemical resistance. The bonds between carbon and fluorine atoms are extremely strong, making the chemical structure virtually unbreakable. Since polymers with high levels of fluorine are more stable and less chemically reactive, Perfluoroelastomers show immunity from chemical attack due to saturation along the polymer’s backbone. There are no double bonds to be attacked by degradants such as oxygen, ozone, UV light, or harsh chemicals. Perfluoroelastomers trace their lineage back to the late 1960s, when chemists at DuPont laboratories pioneered Perfluoroelastomer what came to be known as Kalrez®. In fact, they combined the chemical resistance of Teflon® and the elasticity of fluorocarbon – Viton® into a fully-fluorinated polymer that could be cross-linked and allowing the material to stay resilient even in temperatures approaching 320°C.
PERFLUORELASTOMER PERFORMS WELL IN:
- Most chemical & petrochemical situations
PERFLUORELASTOMER DOES NOT PERFORM WELL IN:
- Uranium hexafluoride
- Fully halogenated Freon®
- Some fluorinated solvents
Chloroprene Rubber - Neoprene
ASTM D1418 Designation: CR
ASTM D2000, SAE J200 Type / Class: BC, BE
STANDARD COLOR: Black
HARDNESS RANGE: 30-90 SHORE A Durometer
TRADE NAMES: Neoprene® (DuPont), Baypren® (LANXESS)
RELATIVE COST: Low / Medium
GENERAL TEMPERATURE RANGE: -40°C to +121°C
Chloroprene was among first synthetic materials developed as an
oil-resistant substitute for natural rubber, it an excellent choice for industrial applications due to its, abrasion resistance, resilience, elongation, low temperature flexibility, and excellent bonding ability.
Chemically known as polychloroprene but often referred to by the trade name Neoprene®, chloroprene was one of the first synthetic materials developed as an oil-resistant substitute for natural rubber. Neoprene’s molecular structure closely mirrors that of natural rubber, with the exception that a chlorine atom has replaced a methyl (CH3) sidegroup. Presence of a chlorine atom in each repeating unit increases the compound’s polarity and improves its resistance to hydrocarbon fluids, despite the presence of a double bond in the main chain. Because the chlorine atom essentially deactivates the double bond, chloroprene is more resistant to oxygen, ozone, and UV light than similarly unsaturated polymers. Due to the similarity of their structures, natural rubber and chloroprene are generally comparable in their good strength, abrasion resistance, resilience, elongation, and strain crystallization characteristics. Both also offer a similar low fatigue property, low heat build-up, low temperature flexibility, and excellent bonding ability. Chloroprene surpasses natural rubber in its resistance to aging, heat, oils, ozone, and solvents.
CHLOROPRENE PERFORMS WELL IN:
- High aniline point petroleum oils
- Mild acids
- Refrigeration seals (resistance to Freon® & ammonia)
- Silicone oil & grease
- Water
92 CHLOROPRENE
CHLOROPRENE DOES NOT PERFORM WELL IN:
- Hydrocarbons (aromatic, chlorinated, nitro)
- Ketones (MEK, acetone)
- Phosphate ester fluids
- Strong oxidizing acids
Millable Polyurethane Rubber
ASTM D1418 Designation: NA
ASTM D2000, SAE J200 Type / Class: NA
STANDARD COLOR: Black / Orange
HARDNESS RANGE: 30-98 SHORE A (60 shore D) Durometer
TRADE NAMES: Millathane® (TSE Industries Inc.), Monothane™ (DOW)
RELATIVE COST: Medium
GENERAL TEMPERATURE RANGE: -55°C to +100°C
Polyurethane rubber provides the highest abrasion resistance of any rubber, synthetic or natural.
Millable Polyurethane Rubber exhibit a combination of physical properties not found in natural or other synthetic rubbers and makes a significant contribution to high-performance rubber parts. Millable Polyurethane Rubber are divided to two grades, Polyester grades and Polyether grades, each exhibit different advantages. Polyester types of polyurethane rubber feature excellent resistance to oil, fuel and solvents at moderate temperatures and are also better in sliding abrasion resistance. Polyether types are more hydrolytically stable and are resistant to impingement abrasion due to their high resilience. Urethanes generally have poor resistance to chlorinated hydrocarbons and ketones. Urethanes are not known for their resistance to acids and bases, and they are affected by water, especially at elevated temperatures. Polyester urethanes are especially affected by these materials as they can undergo hydrolysis where the polymer is degraded. Stabilizers can protect polyester urethanes from hydrolysis to a limited extent. The key properties of a millable polyurethane rubber include excellent abrasion resistance, outstanding resilience characteristics, low temperature flexibility, excellent ozone and weather resistance, load bearing ability, outstanding oil resistance, resistance to nitrogen permeability. Low resilience compounds have excellent vibration damping characteristics and are used in instrument packaging and other vibration damping applications. High resilience compounds tend to have lower heat build-up in dynamic applications such as rubber covered rollers.
Applications that take advantage of the potential millable urethanes are in automotive industry for shock absorbing and bumpers, vibration isolators, bushings, bearings and in other industrial applications for diaphragms, O-rings and gaskets, military dust covers, airplane deicing bladders, belting, rubber covered rollers, solid tires, and athletic footwear.