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Proceedings Paper

On-Line FTIR Measurement Of The DEG-Content In Molten PETP Using A High Pressure, High Temperature Flow Cell.
Author(s): Ralph K. Stengler; Gerald Weis
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Paper Abstract

Polyester, especially polyethylene terephthalate (PETP), have a wide range of use, e.g. synthetic fibres and films. They are usually made by polycondensation of ethylene glycol and terephthalic acid. The remaining content of ethylene glycol (in, our case diethylene glycol DEG) gives an important information about the status of the polycondensation, which determines the mechanical properties of the polymer. In order to get detailed information about the PETP quality during the production it is of interest to measure and control the DEG-content in the PETP melt. During the classical preparation of a sample, occasionally there are changes in the chemical composition of the polymer (e.g. a degassing of monomers is possible). Therefore an AUTOMATIK IROS-100 infrared on-line system was used to avoid those errors since this system directly analyzes the polymer melt at the process temperature in a side-stream of the main polymer line. The molten polymer coming from a bypass of the polymer line is conveyed by a pressure controlled gear pump through a specially developed infrared cell. A special preparation of the sample is not needed. It was possible to quantify the DEG-content in PETP, which was in the range of 0.5 % - 3 %, using an infrared absorption peak with a peak location of approx. 3334 cm-1. It could be demonstrated that the moisture content of the PETP did not influence the above mentioned results. The accuracy of this method was better than 0.2 %.

Paper Details

Date Published: 1 December 1989
PDF: 1 pages
Proc. SPIE 1145, 7th Intl Conf on Fourier Transform Spectroscopy, (1 December 1989); doi: 10.1117/12.969585
Show Author Affiliations
Ralph K. Stengler, Automatik GmbH (Wes t Germany)
Gerald Weis, Automatik GmbH (Wes t Germany)

Published in SPIE Proceedings Vol. 1145:
7th Intl Conf on Fourier Transform Spectroscopy
David G. Cameron, Editor(s)

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