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Explanation of Plastic Types

AMORPHOUS

  • Tough
  • Rigid
  • Good mechanical strength (higher with glass/carbon)
  • Good chemical resistance (poor in aromatic hydrocarbons)
  • Wide thermal operating range
  • Excellent creep resistance
  • Excellent dimensional stability
  • Fair/good H2O resistance
  • Very good machinability
  • Continuous use temperature below Tg (glass transition temperature)

Example

  • PES (Polyethersulfone), PEI (polyetherimide), some polyimides

CRYSTALLINE

  • Resilient
  • Elastic
  • High mechanical strength (higher with glass/carbon)
  • Excellent chemical resistance
  • High continuous use temperature (above Tg)
  • Good creep resistance (improved with fillers)
  • Fair dimensional stability, if molded and annealed properly
  • Very good machinability

Example 

  • PEEK (Polyetheretherketone)
arlon-machining-solutions-image1

CONVENTIONAL THERMOSETS

  • Hard
  • Brittle
  • Fair/poor mechanical strength (fillers necessary)
  • Good chemical resistance
  • Very wide operating range
  • Excellent creep resistance
  • Excellent dimensional stability
  • Very poor H2O/steam resistance
  • Poor to excellent machinability, depending on specific grade of material

Example

  • Epoxy, BMI (bismaleimide), some polyimides


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