An Intriguing Array of Extrudate Patterns in Long-Chain Branched Polymers During Extrusion
Journal article, 2023

The present study highlights a range of surface and volume extrudate patterns that can be detected during the extrusion flow of long-chain branched polymers. Thus, four linear low-density polyethylenes (LDPEs) have been extruded using a single-screw extruder coupled to an inline optical imaging system. The selected LDPEs are selected to outline the influence of molecular weight and long-chain branching on the types of melt flow extrusion instabilities (MFEI). Through the inline imaging system, space–time diagrams are constructed and analyzed via Fourier-transformation using a custom moving window procedure. Based on the number of characteristic frequencies, peak broadness, and whether they are surface or volume distortions, three main MFEI types, distinct from those typically observed in linear and short-chain branched polymers, are identified. The higher molecular weight, low long-chain branching LDPEs exhibited all three instability types, including a special type volume instability. Independently of the molecular weight, higher long-chain branching appeared to have a stabilizing effect on the transition sequences by suppressing volume extrudate distortions or limiting surface patters to a form of weak intensity type.

long-chain branched polymers

inline imaging

melt flow instabilities

spectral analyses

Author

Sajjad Pashazadehgaznagh

Chalmers, Industrial and Materials Science, Engineering Materials

Alexandra Aulova

Chalmers, Industrial and Materials Science, Engineering Materials

Christos K. Georgantopoulos

VAT Vakuumventile AG

Marko Bek

Chalmers, Industrial and Materials Science, Engineering Materials

Iakovos Vittorias

EuropTec Polymer

Ingo FC Naue

Karlsruhe Institute of Technology (KIT)

Manfred Wilhelm

Karlsruhe Institute of Technology (KIT)

Roland Kádár

Chalmers, Industrial and Materials Science, Engineering Materials

Macromolecular Materials and Engineering

1438-7492 (ISSN) 1439-2054 (eISSN)

Vol. 308 8 2300088

Modeling and optimization of biocomposite processing

Stora Enso AB, 2019-11-01 -- 2025-02-28.

Knut and Alice Wallenberg Foundation, 2019-11-01 -- 2025-02-28.

Subject Categories

Materials Engineering

Textile, Rubber and Polymeric Materials

Areas of Advance

Production

Materials Science

DOI

10.1002/mame.202300088

More information

Latest update

3/7/2024 9