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Evaluation of commercial purge compounds on a laboratory film blower
Dissertation (MSc (Chemistry))--University of Pretoria, 2006.
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| Format: | Thesis |
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University of Pretoria
2013
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| _version_ | 1867613452000821248 |
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| access_status_str | Open Access |
| author2 | Focke, Walter Wilhelm |
| author_browse | Focke, Walter Wilhelm |
| author_facet | Focke, Walter Wilhelm |
| collection | Thesis |
| dc_rights_str_mv | © 2003 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Chemistry))--University of Pretoria, 2006. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27808 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:36:21.928Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27808 Evaluation of commercial purge compounds on a laboratory film blower Focke, Walter Wilhelm upetd@up.ac.za Govender, Morgan Cleaning compounds Plastic industry and trade Machines cleaning UCTD Dissertation (MSc (Chemistry))--University of Pretoria, 2006. Purging compounds allow for rapid colour and material changes in plastics converting machines. They have both a cleaning and a purging action. The cleaning action refers to the removal of contaminants, e.g. carbon deposits, from the die, barrel and extruder-screw surfaces. This mechanism relies on conventional detergency in combination with high wall shear stresses. The purging action refers to the observed narrowing in the residence time distribution and is less well understood. The action of a purge compound may encompass both the cleaning and purging mechanisms in order to achieve the desired effect. In industry the effectiveness of a purge is determined by a visual observation of the extrudate. Therefore, a scientific method was required to quantitatively determine the efficiency of each purging mechanism under a set of fixed experimental conditions. In this study, a method was developed using a laboratory film-blower, which made use of a phthalocyanine blue pigment to impart colour to the film produced. The method was used to test the efficiency of various commercial purge compounds in switching the colour of film from blue to clear. The analysis was achieved by measuring the residual pigment concentration in the blue polymer film using a UV -Visible spectrophotometer. Commercial purge compounds function by means of various mechanisms such as filler abrasion, solvent dissolution, the dislodging of deposits with the aid of surfactants, etc. This study also considered the use of slip additives as an additional purging mechanism. In proposing that slip additives can contribute to a purging action, several slip additives where tested in polyethylene (PE), polypropylene (PP) and acrylonitrile butadiene styrene (ABS). The slip additives polypropylene wax and polyamide showed a significant increase in the MFI of PE whereas the additives polar wax and polyamide exhibited a slight increase in MFI of PP. Three additives, namely, polyamide, polypropylene wax and polar wax had showed noticeable improvement on the MFI of ABS. The slip additives that showed a significant improvement in polyethylene were tested together with six different commercial purge compounds. These compounds were tested for their colour change efficiency using polyethylene and switching from blue to clear in a laboratory film blower. It was found that the slip mechanism contributes very little to the purging action. Polymeric materials tend to adhere to hot metal surfaces. When the material continues to adhere to the metal after cooling down, cleaning of the processing equipment becomes very difficult. A purge manufactured by the CSIR, Pretoria, exhibited this problem. This study also covers an investigation into overcoming the adhesion problem of this purging compound. Chemistry unrestricted 2013-09-07T12:22:26Z 2005-09-07 2013-09-07T12:22:26Z 2003-09-01 2006-09-07 2005-09-07 Dissertation Govender, M 2003, Evaluation of commercial purge compounds on a laboratory film blower, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/27808 > H920/ag http://hdl.handle.net/2263/27808 http://upetd.up.ac.za/thesis/available/etd-09072005-121536/ © 2003 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Cleaning compounds Plastic industry and trade Machines cleaning UCTD Evaluation of commercial purge compounds on a laboratory film blower |
| title | Evaluation of commercial purge compounds on a laboratory film blower |
| title_full | Evaluation of commercial purge compounds on a laboratory film blower |
| title_fullStr | Evaluation of commercial purge compounds on a laboratory film blower |
| title_full_unstemmed | Evaluation of commercial purge compounds on a laboratory film blower |
| title_short | Evaluation of commercial purge compounds on a laboratory film blower |
| title_sort | evaluation of commercial purge compounds on a laboratory film blower |
| topic | Cleaning compounds Plastic industry and trade Machines cleaning UCTD |
| url | http://hdl.handle.net/2263/27808 http://upetd.up.ac.za/thesis/available/etd-09072005-121536/ |