Online Detection of Clear Point in Esterification Process of Polyester Production Based on Raman Spectroscopy

KeyWord:Raman spectroscopy  polyester  online detection  qualitative analysis  fluorescence suppression

Abstract:

      Current manual sampling and analysis methods,such as refractive index measurement,chromatography,etc.,have complex operations,time lags and human errors.Therefore,they cannot be used to evaluate the esterification process in polyester production in real time and determine the clear point of the reaction.In this article,an online Raman analysis system with 1 064 nm as the laser wavelength was set up to collect continuously the spectra of the esterification reaction between terephthalic acid(PTA) and 1,3-propanediol(PDO) to create poly(tri methylene terephthalate)(PTT),while using Savitzky-Golay algorithm to make baseline correction on the collected spectra.The principal component analysis was used to extract the spectral information.Based on the principle of esterification process,a qualitative analysis method was established to determine the clear point by using the area ratio for Raman characteristic peaks of benzene loop located near 1 604 cm-1 and ester group located at 1 720 cm-1.Results showed that the developed Raman spectroscopy could accurately reflect the clear point in the esterification process of polyester prodction,With the advantages of good real time performance,simple operation and rapid analysis,it provides a reference for the process control and product quality control of polyester production.