Moldability analysis of several types of polypropylenes using flow-length measurement

Document Type : Original research

Author

Polymeric materials research department, New materials research institute, Alexandria, Egypt

Abstract

The suitability of a polymer to be processed by injection molding is called moldability. The technicians in injection molding companies tend to estimate moldability by using a parameter named Melt Flow Index (MFI), which however can be often misleading since it represents the ability of a melt to flow in specific conditions, very different from the ones that the polymer encounters during injection molding. A much significant parameter is the so-called flow-length, which is the length reached by a polymer during injection molding in a thin cold cavity. In this work, three commercial grades of polypropylene were injection molded in a cold thin cavity and the flowlengths were measured in function of injection pressure and temperature. The results obtained were correlated with the rheological parameters. The results demonstrate that the MFI is misleading as a technical parameter for the moldability of polypropylene. An empirical equation is proposed to describe the flow-length of polypropylene in function of injection pressure.

Keywords

References

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History

  • Receive Date: 17 January 2023
  • Revise Date: 02 April 2023
  • Accept Date: 08 April 2023

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