POLYMER PROCESSING

See Discussion on Polymers and How They Deform in The Handouts

POLYMER PROPERTIES

MOLECULAR STRUCTURES

AMORPHOUS AND CRYSTALLINE POLYMERS

Characteristic Behavior of PolymersETemperatureGlassy RegimeLeathery RegimeRubbery RegimeLiquid/Melt RegimeBelow 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.TgTypically 1 3 GPaTypically 0.1 GPaTmelt

POLYMER CHARACTERISTICS

ELONGATION / NECKING BEHAVIOR

INJECTION MOLDING

INJECTION MOLDING OF A PART

DIE SWELLManifestation from viscoelastic behavior

COATED WIRE FABRICATION

COMPRESSION MOLDING

TRANSFER MOLDING

EXTRUSION BLOW MOLDING

INJECTION BLOW MOLDING

COMPOSITE FABRICATION

PREPREG FABRICATION IN POLYMERIC COMPOSITE MANUFACTURING PROCESS

PULTRUSIONBeing used for fabricating golf rods, antennas for satellites and space shuttles, etc. Many composite shapes can be fabricated in this manner.