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Molded Dimensions works in both of the basic
types of elastomers - Rubber and Polyurethane.
Each of those can be specifically formulated to provide the
optimum properties to your product for its unique application.
The following is a brief overview of the properties and applications
of the most common type of each basic material.
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Rubber : |
Natural Rubber
Natural rubber is among the strongest, yet lowest cost, of
all of the members of the rubber family. Possessing excellent
dynamic and resistance to fatigue properties, it is still
a highly utilized material. However, it has limited resistance
to oils and environmental factors such as Ozone, and has been
replaced by synthetic rubbers for many applications. It still
has applicability for applications such as bellows, boots,
bumpers, bushings, shock mounts, and wear pads.
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Fluorocarbons
Originally developed in the 50’s, and destined for
use in many aerospace applications, Fluorocarbons provide
outstanding resistance to high heat, and a wide variety of
oils, fuels, acids, and solvents. With poor resistance to
tear and cut growth, and because of its high price, fluorocarbon
is generally used only in static applications requiring excellent
stability under extremely severe operating conditions. Applications
include compression seals, diaphragms, gears, head gaskets,
piston cups, seals, and valve liners.
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EPDM
EPDM has a set of physical properties that make it suitable
for a wide range of applications, but especially outdoor and
other applications that require good heat, ozone, and water
resistance. Its limitations are in applications that require
resistance to oil and hydrocarbons. Typical applications include
food processing, gaskets, grommets, oxygenated solvents, and
seals.
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Neoprene
Neoprene was one of the first synthetic rubbers developed.
It adheres very well to fabrics and metals and has outstanding
toughness and resistance to damage caused by flexing and twisting.
The basic chemical composition is polychloroprene which then
can be modified with other chemicals to yield a family of
products with a fairly broad range of chemical and physical
properties. Typical applications include bushings, gaskets,
grips, grommets, and hoses.
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Nitrile
Nitrile rubber in many applications becomes an economic
substitute for neoprene, and does have better resistance to
oil and gasoline. However, it has poorer resistance to ozone,
sunlight, and natural aging. Properties of Nitrile can be
modified for particular applications by varying the ratios
of acrylonitrate and butadiene, and by the addition of polyvinyl
chloride resins. Typical applications include bushings, diaphragms,
fuel lines, grommets, hoses, rollers - carboxylated, and seals.
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Butyl
Butyl is chemically unlike natural rubber or other synthetic
elastomer in that it is inherently resistant to ozone and
corrosive chemicals, including some mineral acids, ketones,
and phosphate-ester type hydraulic fluids. Limitations relate
to creep, cold flow, and compression set. Typical of appropriate
applications are bladders and dampeners.
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Silicone
Silicone rubber is a unique synthetic elastomer made from
a cross-linked polymer which is reinforced with silica.Its
most outstanding feature is its ability to retain rubbery
properties through extremes in temperature. It is the most
heat resistant elastomer in the market today and the most
flexible at low temperatures. Because silicone is relatively
expensive, it is not normally used unless extreme temperature
resistance (-150 to 500F) is essential. Typical applications
include diaphragms, high rollers, medical and food applications,
seals, and temp.
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Styrene Butadiene
SBR is much like natural rubber in most of its properties
and is the lowest cost and highest volume elastomer available.
Although its physical properties are slightly poorer than
natural rubber, SBR is tougher and slightly more resistant
to heat and flex cracking and can be readily substituted for
natural rubber in many applications with significant cost
savings. Typical applications include boots, bumpers, foot
pads, grommets, and wheels.
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Hydrin
Hydrin (Epichlorohydrin) is a specialty polyether elastomer
that appears to possess a combination of many desirable properties
of nitrile and neoprene. On the negative side, its adhesion
to fabrics and metals is much inferior to neoprene. Different
polymer combinations are possible to on those adhesion properties
as well as create improved physical and chemical resistance
properties. Typical applications include air tubes, boots,
fuel lines, primer bulbs, and seals.
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Polyurethane
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Urethane is noted for its combination of hardness with elasticity,
as well as its outstanding abrasion resistance and tear strength.
It is available as either ether or ester based and can be
processed in a cast process or in millable gum form in conventional
rubber processes. Urethane use is usually limited to applications
that require a combination of its outstanding properties of
toughness, tear strength and abrasion resistance due to material
cost. |
Polyester
Ester based urethanes are the superior in resistance to
abrasion and heat. Typical applications include bumpers, liners,
scrapers, squeegees, and wear pads.
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Polyether
Ether based urethanes are superior in flexibility at low
temperatures. Typical applications include coupling, drive
wheels, and rollers.
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