POLYMER PROCESSING

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POLYMER PROCESSING
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See Discussion on Polymers and How They Deform in
The Handouts
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POLYMER PROPERTIES
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MOLECULAR STRUCTURES
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AMORPHOUS AND CRYSTALLINE POLYMERS
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Characteristic Behavior of Polymers
Typically 1 3 GPa
Leathery Regime
E
Rubbery Regime
Glassy Regime
Liquid/Melt Regime
Typically 0.1 GPa
Tmelt
Tg
Temperature
Below the glass transition temperature, the
molecules are extremely restricted in motion due
to thermal energy i.e., they are frozen in.
Most materials have limited ductility or are even
brittle brittle below Tg (e.g., polystyrene),
while others (mainly thermoplastics, e.g.,
polycarbonate) can have good ductility even below
Tg. The curve is sensitive to the time of
loading, and the transition points shift to the
right if the rate of loading is fast. The
converse occurs if the rate of loading is
slow. The liquid/fluid like domain does not exist
for epoxies or polyesters, which are highly
cross-linked by the hardening agent or catalyst.
These materials go through the leathery regime
(which is quite narrow for most polymers) and
then disintegrate at high temperatures). In
rubbers, vulcanization can raise the plateau
associated with the rubbery regime.
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POLYMER CHARACTERISTICS
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ELONGATION / NECKING BEHAVIOR
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INJECTION MOLDING
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INJECTION MOLDING OF A PART
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DIE SWELL
Manifestation from viscoelastic behavior
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COATED WIRE FABRICATION
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COMPRESSION MOLDING
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TRANSFER MOLDING
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EXTRUSION BLOW MOLDING
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INJECTION BLOW MOLDING
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COMPOSITE FABRICATION
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PREPREG FABRICATION IN POLYMERIC COMPOSITE
MANUFACTURING PROCESS
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PULTRUSION
Being used for fabricating golf rods, antennas
for satellites and space shuttles, etc. Many
composite shapes can be fabricated in this manner.