Wareneingangskontrolle von rezyklierten und Neuware-Polypropylenen mittels Folienextrusion

Translated title of the contribution: Incoming goods inspection of recycled and new polypropylene by means of film extrusion

Valentina Wögerbauer

Research output: ThesisMaster's Thesis


The purpose of this master's thesis was to evaluate the possibilities for improving the quality control for incoming virgin and recycled materials on a laboratory extruder. In addition to the values already used, such as pressure and mass output, the measured parameters film width, neck-in and edge beading were examined more closely. The samples were produced using a wide slit film tool, whereby the neck-in was documented using a grid plate and the geometry data for edge beading was measured using a slide gauge. With a view to investigate the relationship between the rheological properties and the selected target variables, the films produced were measured with a plate-plate rheometer. To determine the actual shear rates and viscosity conditions in the die, representative values were approximated analytically and compared with the measured values. In addition, differential scanning calorimetry (DSC) measurements were used to determinemthe mass fraction of the compound components and their crystallinity.The materials selected consisted of four virgin polypropylene (PP) materials with different melt flow rates (MFR), one linear low-density polyethylene (LLDPE) and three additives. To demonstrate the effect of the individual components on recyclates, blends were produced with three different post-consumer polypropylenes which were processed into films and analyzed using the same methodology. The generated data sets from the extruder testings, rheometry and differential scanning calorimetry were correlated and analyzed. It was shown that the actual shear rates and viscosities could be approximated using the analytical calculation. No correlation was observed for mixtures with low-viscosity materials. A qualitative distinguishment of the measured parameters was more difficult for mixtures with a blend component fraction of less than 10 m%, as these were found in a tight value range. The results showed that the film width and the neck-in are interdependent. The virgin PP products and the recyclates were influenced by the LLDPE in the same way. In terms of edge beading, viscosity, and crystallinity, however, the LLDPE had, compared to the virgin PP, either no effect or an opposite effect on the recycled PP. The evaluation of the DSC revealed that the measured melt enthalpies do not correspond to the actual proportion of the foreign polymer present due to impaired crystallization. The conducted tests showed that the potential of the methodology has not yet been exhausted and that the selected target values are suitable for regular operation. However, the measurement setup indicated various sources of inaccuracy, which is why this design is only suitable for a rough assessment.
Translated title of the contributionIncoming goods inspection of recycled and new polypropylene by means of film extrusion
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Krziwanek, Thomas, Supervisor (external), External person
  • Holzer, Clemens, Supervisor (internal)
  • Kaineder, Dominik, Co-Supervisor (external), External person
Award date22 Mar 2024
Publication statusPublished - 2024

Bibliographical note

embargoed until 05-02-2027


  • film extrusion
  • polypropylene recyclates
  • neck-in effect
  • edge beading
  • rheometry

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