title: Monitoring of emulsion polymerization reactors by Raman spectroscopy: calibration model maintenance.
abstract: Fourier transform (FT)-Raman combined with partial least squares regression (PLS-R) calibration models allows the accurate monitoring of solids content, copolymer composition, and free amounts of monomers in starved semi-batch emulsion copolymerizations. The calibration models remain valid as long as the spectrometer and the measuring conditions are unchanged. Unfortunately, maintenance and/or repairing of the spectrometer result in changes in the relative intensities of the peaks of the Raman spectrum, reducing the performance of the calibration models. Therefore, a strategy for the up-date of the PLS-R calibration models is needed. Strategies for calibration model maintenance were assessed, and we found that the best strategy was to build a new model composed of the old PLS-R model plus a PLS-R model able to account for the model mismatch of the old model.
authors.affiliation: Institute for Polymer Materials, POLYMAT, and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, Apdo, 1072, 20080 Donostia-San Sebastián, Spain.
authors.forename: Oihana
authors.initials: O
authors.lastname: Elizalde
authors.forename: José M
authors.initials: JM
authors.lastname: Asua
authors.forename: Jose R
authors.initials: JR
authors.lastname: Leiza