Polycarbonate

Symbol: PC
Crystallinity: Amorphous
Trade Names: Calibre / Lexan / Makrolon

Learn more about Processing Polycarbonate.

Description:

Fotolia_1753025_XL.jpgPolycarbonate has high clarity, exceptionally high impact strength over a wide temperature range, dimensional stability and heat and flame resistance. Available in a wide range of grades based on viscosity. The let-down ratio is from 1.74 to 5.5 thereby allowing a higher compression ratio screw.






Processing Polycarbonate Considerations:

  • Residence Time: Residence time ranges from 2 to 4 minutes.
  • Back Pressure: 150 PSI or 1500 Plastic Pressure or less.
  • Drying: PC must be dried.
  • RPM: RPM is typically 30 – 100.

Screw Design Based On:

  • Low Compression Ratio
  • Long Transition Length
  • Deep Meter Channel Depth

Other Information:

  • Mixer: When processing polycarbonate, color mixing can be an issue. Colorant to polycarbonate mixes like oil to water. This can require a mixer, however it must be non-shear, like Reiloy Westland Corporation’s Eagle Mixer. Reiloy Westland Corporation’s Eagle mixing screw has also been proven to process clear polycarbonate with great success.
  • Barrier: Barrier designs are not recommended when processing polycarbonate.
  • Custom Design: When processing polycarbonate, a custom designed screw is recommended over a general purpose design. Even though a polycarbonate design is usually based on a low compression ratio, polycarbonate can be processed with higher compression ratios, especially with the Eagle mixer.
  • Recommended Valve: Use a three-piece free-flow style valve when processing polycarbonate.
  • Screw & Barrel Material Recommendation: Polycarbonate can be processed on components manufactured from standard alloys.

Polycarbonate becomes tacky and will stick to the screw once it is overheated. At that point, the properties of the resin have to burn completely out before it will release from the screw, which causes black specs.

Various additives and/or fillers can have an effect on a resin’s process behavior. For more detailed information on processing polycarbonate, please contact Reiloy Westland Corporation.

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