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Shantou Longsheng Technology: Screw and Die Selection for PET vs PP Sheet Extrusion

Time: 2026-10-30 10:09:56.695

The Screw Is the Heart of Sheet Quality

The same extruder fitted with a different screw and die can produce dramatically different sheet. Reading the L/D ratio on a spec sheet is only the first step; what matters is whether the screw design matches the material.

PET and PP Want Opposite Things

  • PET is sensitive to both shear and moisture: excessive shear causes degradation and yellowing, and excess moisture causes bubbles and hydrolysis. The Longsheng LSI series PET/PLA single-screw sheet extruders come with a built-in drying and crystallizing system, and with low-shear screw design they turn recycled bottle flakes into food-grade sheet
  • PP is tough but sensitive to temperature, and multilayer structures are in high demand: the Longsheng DSI-PP multilayer co-extrusion line builds barrier layers and a surface-reprocess / core-regrind structure that balances cost and performance
  • PE sheet is flexible and ductile; the Longsheng SI-PE series stabilizes output for its low melt strength

Die and Temperature Profile

A coat-hanger die with adjustable restrictor bars is the foundation of cross-profile uniformity. Longsheng's patented interval-heating technology brings the barrel temperature profile to steady state faster and narrows down-profile variation.

About Longsheng

Founded in 1998, Shantou Longsheng Industry Co., Ltd. is a certified high-tech enterprise. Learn more at https://www.stlongsheng.com

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