skip to main content

Title: Influences on particle shape in underwater pelletizing processes

Underwater pelletizing has gained high importance within the last years among the different pelletizing technologies, due to its advantages in terms of throughput, automation, pellet quality and applicability to a large variety of thermoplastics. The resulting shape and quality of pellets, however, differ widely, depending on material characteristics and effects not fully understood yet. In an experimental set-up, pellets of different volumes and shapes were produced and the medium pellet mass, the pellet surface and the bulk density were analyzed in order to identify the influence of material properties and process parameters. Additionally, the shaping kinetics at the die opening were watched with a specially developed camera system. It was found that rheological material properties correlate with process parameters and resulting particle form in a complex way. Higher cutting speeds were shown to have a deforming influence on the pellets, leading to less spherical s and lower bulk densities. More viscous materials, however, showed a better resistance against this. Generally, the viscous properties of polypropylene proofed to be dominant over the elastic ones in regard to their influence on pellet shape. It was also shown that the shapes filmed at the die opening and the actual form of the pelletsmore » after a cooling track do not always correlate, indicating a significant influence of thermodynamic properties during the cooling.« less
Authors:
; ; ;  [1]
  1. Institut für Kunststofftechnik, University of Stuttgart (Germany)
Publication Date:
OSTI Identifier:
22280710
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1593; Journal Issue: 1; Conference: PPS-29: 29. international conference of the Polymer Processing Society, Nuremberg (Germany), 15-19 Jul 2013; Other Information: (c) 2014 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BULK DENSITY; COOLING; PARTICLE SIZE; PELLETS; POLYPROPYLENE; SHAPE; SURFACES; THERMODYNAMIC PROPERTIES; THERMOPLASTICS