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Rubber Selection - A Guide to Outline Properties
The information below is intended to give a broad overview of the
properties of a number of different rubbers. This is intended
to aid in the selection of rubbers for particular service conditions.
A guide of this sort is only intended as a first step in selection
- mainly to eliminate materials which are obviously unsuitable. Beyond
this, factors such as component size can have a major influence on
properties such as oxidation resistance and oil resistance. Also,
the properties of a vulcanized rubber can be significantly influenced
by details of the compounding. Practical materials will have, in
addition to the base polymer, fillers, anti-degradants, crosslinking
agents, accelerators etc. All of these can have an influence on the
physical and chemical stability of the finished material. In critical
applications it is therefore advisable to give considerable thought,
or take advice, on the formulation of the compound. As the potential
for 'tailoring' compound to specific applications is essentially
limitless, it is often advisable to carry out preliminary qualification
tests to ensure that the compound chosen will perform as intended.
Trade names are given to assist in recognition, but the list is necessarily
only partial, and is given in alphabetical order. Trade names are generally
registered and/or copyright and are indicated by an asterisk after the
name - see below.
Abbreviations used are those based on latest ISO recommendations.
The temperature ranges quoted are only a rough guide, because the temperature
range possible will depend upon the particular application, and may depend
on detailed differences between alternative versions of the same rubber.
In some cases greater extremes of temperature can be tolerated than indicated
below.
The information given below is given in good faith, but MERL can accept
no responsibility for the information. Normal screening procedures should
be operated before any material is selected for service.
Owners of trade names
Trade Names are distinguished in the tables below by being listed
only under the heading 'Trade Names', and are each followed by an
asterisk. This list indicates the owners of registered trademarks.
Because of mergers/take-overs the name of the company indicated against
the proprietary/trade name may not always be the current owner. We
will be pleased to make any changes of which we are informed. |
Rubber
Types
| Common name |
ACRYLIC RUBBER |
| Chemical name |
Alkyl acrylate copolymer |
| Abbreviation |
ACM |
| Trade names |
Hytemp* |
| The outstanding property of this material
is its resistance to hot oil and to oxidation. It is suitable for
continuous use at temperatures up to 150C, and intermittent exposure
up to about 180C. This is provided it is not exposed to water or moisture
-
to which it has poor resistance. It is generally not suitable for use
much below -10C and has poor resistance to acids and bases. It has only
modest dynamic properties and rather poor compression set. Widely used
in automotive transmissions and hoses.
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| Common name |
BUTADIENE RUBBER |
| Chemical name |
Polybutadiene |
| Abbreviation |
BR |
| Trade names |
|
| This material has a very low glass transition
temperature in the region -75C to -100C. This results in very low
hysterisis and good flexibility at ambient temperatures and these
properties are maintained to temperatures well below zero. It has high
abrasion resistance in severe conditions. Mainly used in tyres in blends
with natural rubber and SBR.
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| Common name |
BUTYL RUBBER |
| Chemical name |
Isobutylene-isoprene copolymer |
| Abbreviation |
IIR |
| Trade names |
|
| This rubber has very high impermeability to gases and
is hence used for the inner tubes of pneumatic tyres, and in vacuum and
high pressure applications. It has an unusually broad loss peak so that,
despite having a glass transition temperature as low as -65C, it
displays high damping at ambient temperatures It has good ozone,
weathering, heat, and chemical resistance. Not suitable for use in
contact with mineral oils.
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| Common name |
CHLOROBUTYL |
| Chemical name |
|
| Abbreviation |
CIIR |
| Trade names |
|
| Similar in properties to butyl rubber (qv), but with
improved ozone and environmental resistance and greater stability at
high temperatures. Improved compatibility with other rubber types in
blends.
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| Common name |
CHLORINATED POLYETHYLENE |
| Chemical name |
|
| Abbreviation |
CPE |
| Trade names |
|
| Good chemical resistance to hydrocarbon fluids and
elevated temperatures. Used for hose linings. Poor mechanical strength.
Mechanical properties may deteriorate above 100C.
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| Common name |
CHLOROSULPHONATED POLYETHYLENE |
| Chemical name |
|
| Abbreviation |
CSM |
| Trade names |
Hypalon® |
| This is a material with Neoprene polychloroprene
'plus' qualities. It is suitable for continuous use up
to about 130C and intermittent use up to some 30C above this. It has
excellent resistance to oxygen, ozone and most chemicals, including
water, but has poor fuel resistance. It has low gas permeability. It
has poor compression set resistance which limits its usefulness in dynamic
sealing applications.
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| Common name |
EPICHLORHYDRIN |
| Chemical name |
|
| Abbreviation |
CO |
| Trade names |
|
| High resistance to ageing, oxidation, ozone, and hot
oil. Good resistance to hydrocarbon solvents, moderate low temperature
flexibility. Poor abrasion resistance and electrical properties.
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| Common name |
ETHYLENE ACRYLIC |
| Chemical name |
|
| Abbreviation |
AEM |
| Trade names |
Vamac |
| This has better low temperature performance (to -40C)
and dynamic properties than acrylic (qv), but at the expense of fluid
resistance. It has good compression set resistance, but poor resistance
to aromatic hydrocarbons, strong acids and bases.
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| Common name |
ETHYLENE PROPYLENE RUBBER |
| Chemical name |
Ethylene propylene copolymer, or a terpolymer with a diene |
| Abbreviation |
EPM, EPDM |
| Trade names |
Dutral*, Nordel®, Vistalon* |
| Probably the most water resistant rubber available, and
this resistance is maintained to high temperatures (up to 180C in steam
for peroxide cures). The highest temperature resistance is achieved by
using peroxide cured grades. Has excellent resistance to atmospheric
ageing, oxygen and ozone up to about 150C. It has good resistance to
most water-based chemicals and to vegetable-based hydraulic oils.
However, it has very poor resistance to mineral oils and di-ester based
lubricants.
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| Common name |
FLUOROELASTOMERS |
| Chemical name |
|
| Abbreviation |
FKM |
| Trade names |
Dai-El*, Fluorel*, Technoflon*, Viton® |
| This is a family of rubbers designed for very high
temperature operation. They can operate continuously somewhat in excess
of 200C depending on the grade, and intermittently to temperatures as
high as 300C. They have outstanding resistance to chemical attack by
oxidation, by acids and by fuels. They have good oil resistance.
However, at the high operating temperatures they are weak, so that any
design must provide adequate support against applied forces. They have
limited resistance to steam, hot water, methanol, and other highly polar
fluids. They are attacked by amines, strong alkalis and many Freons.
There are standard and special grades - the latter can be designed to
have special properties such as improved low-temperature resistance.
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| Common name |
HYDROGENATED NITRILE RUBBER |
| Chemical name |
|
| Abbreviation |
HNBR |
| Trade names |
Therban*, Tornac*, Zetpol* |
| The properties of hydrogenated nitrile rubber depend
on the acrylonitrile (ACN) content, and on the degree of hydrogenation.
They can be ‘tailored’ to particular applications, but have
the general advantage over standard nitrile rubber of having higher
temperature resistance and higher strength. They have good high
temperature oil and chemical resistance and are resistant to amines.
They are suitable for use in methanol and methanol/hydrocarbon mixtures
if the correct ACN level is selected. They have good resistance to hot
water and steam. They can have excellent mechanical properties
including strength, elongation, and tear. Also, abrasion resistance,
compression set, and extrusion resistance. For the best properties
peroxide curing is used, unless low hysteresis is required. They are
reported to be satisfactory up to temperatures around 180C in oil. Fully
saturated grades have excellent ozone resistance. They have poor
resistance to some oxygenated solvents and aromatic hydrocarbons.
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| Common name |
ISOPRENE RUBBER |
| Chemical name |
Synthetic cis-polyisoprene |
| Abbreviation |
IR |
| Trade names |
Natsyn* |
| This is the same polymer as natural rubber - but made
synthetically. Essentially similar in properties to natural rubber (qv)
it may be somewhat weaker because it is not 100% the cis isomer.
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| Common name |
NATURAL RUBBER |
| Chemical name |
cis-polyisoprene |
| Abbreviation |
NR |
| Trade names |
|
| The outstanding strength of natural rubber has
maintained its position as the preferred material in many engineering
applications. It has a long fatigue life and high strength even without
reinforcing fillers. Other than for thin sections it can be used to
approximately 100C, and sometimes above. It can maintain flexibility
down to -60C if compounded for the purpose. It has good creep and stress
relaxation resistance and is low cost. Its chief disadvantage is its
poor oil resistance and its lack of resistance to oxygen and ozone,
although these latter disadvantages can be ameliorated by chemical
protection.
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| Common name |
NITRILE RUBBER |
| Chemical name |
acrylonitrile-butadiene copolymer |
| Abbreviation |
NBR |
| Trade names |
Breon*, Chemigum*, Europrene*, Hycar*, Krynac*, Nipol* |
| At temperatures up to 100C, or with special compounding
up to 120C, nitrile rubber provides an economic material having a high
resistance to aliphatic hydrocarbon oils and fuels. Different grades
are available - the higher the acrylonitrile (ACN) content, the higher
the
oil resistance but the poorer is the low temperature flexibility. It
has high resilience and high wear resistance but only moderate strength.
It has limited weathering resistance, and poor aromatic oil resistance.
It can generally be used down to about -30C, but special grades can
operate at lower temperatures.
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| Common name |
PERFLUORO ELASTOMERS |
| Chemical name |
|
| Abbreviation |
FFKM |
| Trade names |
Chemraz*, Kalrez®, Perfluor*, Simriz*, Zalak |
| These are materials having even greater heat and
chemical resistance than the fluoroelastomers. They can be used in
extreme conditions up to temperatures around 300C or even higher with
special compounding. Their disadvantages are difficult processing, very
high cost, poor physical properties at high temperature, and their high
glass transition temperatures which limit their use at low temperatures.
Most materials cannot be used below zero Celsius, and even at normal
ambient temperatures their creep properties are likely to be poor.
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| Common name |
POLYCHLOROPRENE |
| Chemical name |
|
| Abbreviation |
CR |
| Trade names |
Neoprene polychlorprene |
| This rubber has a generally good balance of mechanical
properties and fatigue resistance second only to natural rubber, but
with superior chemical, oil, and heat resistance. It is widely used in
general engineering applications. It is less resistant than natural
rubber to low temperature stiffening but can be compounded to give
improved low temperature resistance. It has good ozone resistance. It is
suitable for use with mineral oils and greases and dilute acids and
alkalis, but is unsuitable in contact with fuels. It has generally
poorer set and creep than natural rubber.
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| Common name |
POLYNORBORNENE RUBBER |
| Chemical name |
|
| Abbreviation |
PNB |
| Trade names |
Norsorex* |
| This rubber is generally used for specialist
applications where a very soft material is required. Materials can be
produced in the range 15 - 25 IRHD with good damping properties, which
is more like a jelly than a conventional rubber. It is therefore used
for vibration absorption. It is not oil resistant and has an upper
temperature limit of around 70C.
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| Common name |
POLYSULPHIDE RUBBER |
| Chemical name |
|
| Abbreviation |
TR |
| Trade names |
Thiokol* |
| Very good resistance to oils, fuels, solvents, oxygen,
and ozone. Impermeable to gases. Poor mechanical properties and poor
heat resistance.
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| Common name |
POLYURETHANE RUBBER |
| Chemical name |
|
| Abbreviation |
AU (polyester) EU (polyether) |
| Trade names |
Adiprene*, Estane*, Genthane* |
| These materials have high tear strength and good wear
resistance. Their upper temperature limit is typically 80C. They have
excellent resistance to weathering and oxidation. They resist
hydrocarbon fuels and mineral oils but some grades hydrolyse in hot
water. They are one of the best rubbers for abrasion resistance and
are therefore used in reciprocating seals. Some grades are castable.
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| Common name |
SILICONE (and FLUOROSILICONE) RUBBER |
| Chemical name |
|
| Abbreviation |
MQ (methyl groups on chain)
VMQ (methyl and vinyl groups)
PMQ
(methyl and phenyl groups)
FMQ (methyl and fluorine groups) |
| Trade names |
Silastic* |
| The outstanding property of these materials is their
very wide temperature range. Typically the range is -60C to 200C and
above, with PMQ down to -90C. They do not have very good physical
properties, but the properties they do have are retained to high
temperatures. FMQ has better oil and water resistance than the others.
They are used in room temperature vulcanizing (RTV) sealants for joints.
Beware corrosion if acetic acid is present as a curing agent.
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| Common name |
STYRENE BUTADIENE RUBBER |
| Chemical name |
|
| Abbreviation |
SBR |
| Trade names |
|
| This is the highest volume general purpose synthetic
rubber. It is very weak unless reinforcing fillers are incorporated.
With suitable fillers it is a strong rubber although not approaching
natural rubber or polychloroprene. Otherwise it has similar chemical
and physical properties to natural rubber, with generally better abrasion
resistance but poorer fatigue resistance.
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| Common name |
TETRA-FLUOROETHYLENE/PROPYLENE |
| Chemical name |
|
| Abbreviation |
FEPM |
| Trade names |
Aflas* |
This is a high temperature polymer capable of operating
in the range 20C to 200C (to 260C in steam). It has good overall
chemical resistance including amines, methanol, steam and hot water.
Its hydrocarbon resistance approaches that of FKM copolymer. It has,
however, poor compression set and a high minimum working temperature.
back to rubber list |
Hypalon®, Nordel®, Viton®,
Kalrez® and
Neoprene polychlorprene are all registered trademarks of DuPont
Dow Elastomers |
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