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Materials:
Plastics
Elastomers
Elastomers and
rubber are differentiated from polymers by the
mechanical property of returning to their original
shape after being stretched to several times
their length. The rubber industry differentiates
between the terms "elastomer" and "rubber" on
the bases of how long a deformed material sample
requires to return to its approximate original
size after a deforming force is removed, and
of its extent of recovery. Synthetic materials
such as neoprene, nitrile, styrene butadiene
(SBR), and butadiene rubber are now grouped
with natural rubber. These materials serve engineering
needs in fields dealing with shock absorption,
noise and vibration control, sealing, corrosion
protection, abrasion protection, friction production,
electrical and thermal insulation, waterproofing,
confining other materials, and load bearing.
As with almost any material,
selecting a rubber for an application requires
consideration of many factors, including mechanical
or physical service requirements, operating
environment, a reasonable life cycle, manufacturability
of the part, and cost.
Manufacturing
rubber parts is accomplished in one of three
ways: transfer molding, compression molding,
or injection molding. The choice of process
depends on a number of factors, including the
size, shape, and function of the part, as well
as anticipated quantity, type, and cost of the
raw material.
Elastomers are
classified as follows:
- Nonoil-resistant rubbers
- Oil-resistant rubbers
- Thermoplastic elastomers
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