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Analysis of pellet shaping kinetics at the die opening in underwater pelletizing processes
Author(s) -
Kast Oliver,
Geiger Kalman,
Grünschloss Eberhard,
Bonten Christian
Publication year - 2015
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.23988
Subject(s) - pelletizing , pellet , pellets , materials science , die (integrated circuit) , deformation (meteorology) , viscosity , underwater , composite material , compounding , process (computing) , polymer , material flow , polypropylene , mechanical engineering , process engineering , computer science , nanotechnology , engineering , ecology , oceanography , geology , biology , operating system
Underwater pelletizing of thermoplastic materials has gained high importance within the chemical and the compounding industry. It is known for producing comparatively spherical pellets with good bulk characteristics. Pellet shapes are determined by the viscous and elastic properties of the melt as well as various process conditions. Therefore, deformation of the melt strands because of the water flow at the die‐hole opening may result in undesired shapes. This is particularly the case when processing polymers of low viscosity. This paper defines an analytical framework describing the pellet formation at the die‐hole opening. Furthermore, a nondimensional DS number is developed as a measure for the deformation sensitivity of different polymer materials. In order to validate this approach, a new camera system and video recording method has been developed, which allows for a visual analysis of the cutting process in underwater pelletizing systems. Examining different materials at various process parameters, this paper identifies the main parameters responsible for pellet deformation and demonstrates how the DS number can be used to anticipate these effects. POLYM. ENG. SCI., 55:1170–1176, 2015. © 2014 Society of Plastics Engineers