On-line determination of the conversion in a styrene bulk polymerization batch reactor using near-infrared spectroscopy

• Published in: Journal of applied polymer science 2002-04, Vol.84 (1), p.90-98
• Main Authors: Lousberg, H. H. A., Boelens, H. F. M., Le Comte, E. P., Hoefsloot, H. C. J., Smilde, A. K.
• Format: Article
• Language: English
• Subjects: Applied sciences; degree of polymerization; Exact sciences and technology; modeling; near-infrared spectroscopy; Organic polymers; Physicochemistry of polymers; Polymerization; polystyrene; Preparation, kinetics, thermodynamics, mechanism and catalysts; sensors
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.10241

A fast on‐line method for measuring the monomer conversion of a styrene batch polymerization reaction with near‐infrared spectroscopy (NIR) has been developed. Multivariate calibration was performed, using polymer samples having temperatures around the set point of the batch reactor (75–85°C) and monomer conversions up to 35%. The calibration model was built in such a way that the effect of the temperature on the predicted conversion of the sample was minimized. The method was validated in a number of batch runs. In these runs, the batch temperature and molar mass distributions of the polymer were varied. At‐line size‐exclusion chromatography was used as a reference method for measuring the monomer conversion. Results show that on‐line conversion monitoring with NIR offered overall an excellent accuracy (∼ 0.32% conversion). For high and low monomer conversions a small bias in the predicted conversion is present. The method proved to be insensitive to both relative large changes (10°C) of the batch temperature and to considerable changes of the molar mass distribution of the polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 90–98, 2002; DOI 10.1002/app.10241