25-08-2017, 09:32 PM
Thermoplastic Materials Engineering Plastics
Thermoplastic Materials.ppt (Size: 3.35 MB / Downloads: 60)
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