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Historical review of die drool phenomenon in plastics extrusion

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dc.title Historical review of die drool phenomenon in plastics extrusion en
dc.contributor.author Musil, Jan
dc.contributor.author Zatloukal, Martin
dc.relation.ispartof Polymer Reviews
dc.identifier.issn 1558-3724 Scopus Sources, Sherpa/RoMEO, JCR
dc.date.issued 2014
utb.relation.volume 54
utb.relation.issue 1
dc.citation.spage 139
dc.citation.epage 184
dc.type article
dc.language.iso en
dc.publisher Taylor & Francis Inc.
dc.identifier.doi 10.1080/15583724.2013.860987
dc.relation.uri http://www.tandfonline.com/doi/full/10.1080/15583724.2013.860987
dc.subject cohesive chain disentanglement en
dc.subject Die drool en
dc.subject flow induced molecular weight fractionation en
dc.subject flow instabilities en
dc.subject wall slip en
dc.description.abstract Die drool phenomenon is defined as unwanted spontaneous accumulation of extruded plastics on die exit face(s) of extrusion die during plastics extrusion process. Such accumulated material builds up on die exit face(s) and frequently or continually sticks onto the extruded product and by this way reduces the quality of the product. When the die drool appears, the extrusion process must be shut down and the die exit face(s) must be manually cleaned, which is time consuming as well as money consuming. Die drool has been observed from the beginning of plastics extrusion and the first published remark about it was made in 1946. For a long time it was considered as only an engineering problem and even if a wide range of suppressing ideas based on modification of extrusion dies, plastics materials, and processing conditions have already been patented, its source remained unclear. During the last few years, a number of experimental as well as theoretical research papers focusing on its fundamental nature have been published. Nowadays, die drool is considered as a fundamental rheological phenomenon. The force which drives the building up of extruded plastics on die exit face(s) is negative pressure (suction) occurring in the die exit edge(s) region where the free surface of the extruded plastics is created. Moreover, two different die drool types (external and internal) exist. The formation mechanisms of external/internal die drool are based on negative pressure occurring in the die exit region together with deformation of free extrudate surface/material separation wherever inside the extrusion equipment, respectively. From the processing point of view, the internal die drool is much more problematic than the external one, primarily due to a higher build up rate and compact shapes of the accumulated drool mass. Two theories of internal die drool formation mechanism based on wall slip theories (flow-induced molecular weight fractionation and stress-induced cohesive chain disentanglement) have been recently proposed and tested. In this historically ordered review, breakthrough works in the field of die drool research are presented, many ways to suppress it are shown, techniques for its quantitative evaluation and experimental methods for its analytical investigation are introduced, external and internal die drool types are explained, and theories of external as well as internal die drool formation mechanism are presented and discussed in depth, which can be especially helpful for plastics extrusion experts as well as for the rheological community. © 2014 Taylor and Francis Group, LLC. en
utb.faculty University Institute
utb.faculty Faculty of Technology
dc.identifier.uri http://hdl.handle.net/10563/1003697
utb.identifier.obdid 43871770
utb.identifier.scopus 2-s2.0-84894579869
utb.identifier.wok 000331523000004
utb.source j-scopus
dc.date.accessioned 2014-04-16T13:35:07Z
dc.date.available 2014-04-16T13:35:07Z
utb.ou Centre of Polymer Systems
utb.contributor.internalauthor Musil, Jan
utb.contributor.internalauthor Zatloukal, Martin
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