Amorphous and Semi-Crystalline Engineering Thermoplastics

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• Amorphous and Semi-Crystalline
• Engineering Thermoplastics
• Materials, properties and applications.

Prepared by the IAPD Education Committee (Module
4) Presented courtesy of Modern Plastics Inc.
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Amorphous Engineering ThermoplasticsKey
Characteristics

• Moderate cost, strength and temperature
  resistance
• Good impact resistance
• Translucency
• Good dimensional stability
• Excellent optical qualities

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Amorphous Engineering ThermoplasticsMaterials

• Polycarbonate (PC)
• Polyphenylene Oxide (PPO)
• Polyphenelyne Ether (PPE)
• Thermoplastic Urethane (TPU)

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Polycarbonate (PC)Strengths

• Excellent clarity
• Excellent toughness
• Good heat resistance
• Excellent electrical properties
• Intrinsic flame-retardancy
• Excellent strength

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Polycarbonate (PC)Limitations

• Continual exposure to hot water causes gradual
  embitterment
• Most aromatic solvents, esters and ketones can
  cause crazing and cracking

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Polycarbonate (PC)Applications

• Vandal resistant windows
• Machine guards
• Outdoor signs
• Sky lights
• Backboards
• Bike, roller blading protective wear

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Modified Polyphenylene Oxide (Mod PPO) Modified
Polyphenylene Ether (Mod PPE) Key Characteristics

• High dielectric strength
• Available in FDA compliant grades
• Less expensive than polycarbonate (PC)
• Good chemical resistance to strong acids, bases
  and water
• Wide range of processing
• Good creep resistance

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Modified Polyphenylene Oxide (Mod PPO) Modified
Polyphenylene Ether (Mod PPE) Applications

• Electrical housings in appliance, computers,
  business equipment, etc.
• Water purification equipment parts
• Insulators
• Gears

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Thermoplastic Polyurethane (TPU)Key
Characteristics

• Wide range of service temperatures
• Wide range of harness options
• Excellent tear resistance
• Excellent compression strength
• Excellent resistance to non polar solvents
• Excellent electrical properties
• Excellent abrasion resistance
• High tensile strength

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Thermoplastic Polyurethane (TPU)Applications

• Impact resistant housings
• Valves
• Water filter caps
• Geophysical cable spacer

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Semi-Crystalline Engineering Thermoplastics Key
Characteristics

• Moderate cost, strength
• Moderate temperature resistance
• Good chemical resistance
• Good bearing and wear properties
• Low COF
• Difficult to bond

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Semi-Crystalline Engineering Thermoplastics
Materials

• Polyamide (PA) Nylon
• Polyoxymethylene (POM) Acetal
• Polyethylene terephthalate (PET)
• Polybutylene terephthalate (PBT)
• Ultra high molecular weight polyethylene
• (UHMW-PE)

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Nylon (PA) Strengths

• Good strength
• Good toughness
• Fair heat resistance
• Good chemical resistance
• Low COF

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Nylon (PA) Limitations

• Strong acidic environments
• Areas where moisture absorption is of concern
• Areas experiencing high operating temperatures

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Nylon (PA) Applications

• Film
• Automotive
• Electrical/electronics
• Consumer goods

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Cast PA vs. Extruded PA

• Extruded nylon can be produced in almost any
  grade
• Cast nylon grades are limited to Type 6, Type 6
  1/2 and some Type 12
• Generally Nylon 6/6 and Nylon 6 (cast or
  extruded) are interchangeable in most
  applications (physical property differences are
  minor)
• Nylon 6/6 is stronger and stiffer than Nylon 6,
  and has more resistance to compression
• Nylon 6 has better elongation values than Nylon
  6/6, providing better ductility
• Cast Nylon can be produced in large profiles and
  custom shapes, and is generally less expensive
  than extruded grades

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Acetal (POM)Strengths

• Good dimensional stability
• Good wear resistance
• Excellent strength
• Excellent stiffness
• Good rigidity
• Low moisture absorption
• Low COF

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Acetal (POM)Limitations

• Centerline porosity in copolymers
• Using copolymer in hot water environments
  (boiling/steam)
• Strong acidic environments
• Strong alkali environments
• Areas experiencing high operating temperatures

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Acetal (POM)Applications

• Bearings
• Bushings
• Valve seats
• Washers
• Nozzles
• Spools
• Cams

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Thermoplastic PolyestersKey Characteristics

• Good range of mechanical properties
• Good dimensional stability
• Superior chemical resistance
• Good electrical properties

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Thermoplastic Polyesters Materials

• Polyethylene terephthalate (PET)
• Polybutylene terephthalate (PBT)

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Polyethylene Terephthalate (PET)Polybutylene
Terephthalate (PBT)Key Characteristics

• High dimensional stability under heat
• High stiffness and hardness
• Good bearing strength
• Good electrical properties
• Good resistance to chemicals
• Good stress-cracking resistance
• Excellent flow characteristics

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Thermoplastic PolyestersApplications

• Pump components
• Automotive components
• Food packaging components
• Insulators

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Thermoplastic PolyestersCaution!

• Watch high temperature environments!
• Use caution when recommending thermoplastic
  polyesters in applications requiring high
  temperature resistance, above 93-121oC/200-250oF.

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Ultra High Molecular Weight PE (UHMW-PE)Strengths

• Highest abrasion resistance and impact strength
  of any plastic
• Very low COF
• Excellent cryogenic (low temperature) material
• Self-lubricating
• FDA/USDA compliant

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Ultra High Molecular Weight PE (UHMW-PE)Limitatio
ns

• Only good until 82oC/180oF
• Not a self-supporting material
• High cost for tooling for custom extrusion and
  custom parts

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Ultra High Molecular Weight PE (UHMW-PE)Applicati
ons

• Guides
• Wear strips
• Liners

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