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Thermoplastic Materials Engineering Plastics

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Engineering Thermoplastics

Replace metallic parts
Strength and stiffness
Retention of properties over range of temperatures
Toughness to withstand incidental damage
Dimensional stability
Low creep
Low CTE
Withstand environmental factors (UV, O2, chemicals)
Shaped easily

Compared to commodity plastics

More expensive
The commodity resins are all lacking some critical property
Some Engineering Thermoplastics are formed through the condensation polymerization process

PA General Family Characteristics

Polarity
Crystallinity
Sharp meltpoint
Strength
Comparison of higher & lower nylon numbers

Processing Nylon

Injection molding
Shrinkage—crystallinity—.018 in/in
Dry it first
Extrusion
Low melt viscosity
Be careful of decomposition
Fibers
Drawing
Crystallization
Orientation

Nylon History

Nature of polymer bonding not understood
Carothers
Difunctional monomers
Polymers—1000 units long
Larger units—molecular still to eliminate water
Control of melting point and length
Many combinations of polyesters
Trying polyamides
Settling on 6,6
Carothers death
3 weeks after patents
Tremendous success
Name
Delawear, Wacra, Norun, Nuron, Nulon, Nilon, Nylon