Multivariate near infrared spectroscopy models to monitor polycondensation production process reactions

Abstract

The control of polycondensation progress in the reactor is usually carried out by the determination of the acid value and the Average Molecular Weight (AMW) using analytical methods that are expensive and time consuming. Alternatively, this work reports the use of near infrared spectroscopy (NIRS), coupled with multivariate calibration techniques, to determine these two parameters. Thus, polycondensations of Adipic Acid with 1,6-Hexanediol were carried out at 130°C and followed in-line using NIRS. Principal Component Analysis (PCA) was used to perform the qualitative analysis of the spectra, whereas Partial Least Squares (PLS) regression was used to develop calibration models between the spectra and the acid value and the average molecular weight of the polymers. The results support that NIRS, in combination with multivariate calibration, is a promising and an accurate method for monitoring the polycondensation process.