On-line Monitoring Of Polyurethane Prepolymer Polymerization By Raman Spectroscopy

Polyurethane material with its superior performance is widely used in the production and living. In the production of polyurethane prepolymer, an important intermediates of polyurethane, the traditional method of analysis and testing has some problem such as complex operation, time-consuming and pollution of the environment. So a rapid, nondestructive and real-time testing method is need to monitor the related indicators. With the advantages of fast, efficient and non-destructive, Raman spectroscopy has been successfully applied in diverse industrial fields in recent years, such as petroleum chemical industry, medicine, pharmacy, archaeological identification, food safety, environmental protection and so on. It have higher demand to the stability of the instrument and environment when Raman spectroscopy used in quantitative analysis and process monitoring. The will be changed by the fluctuation of laser light source or the different relative position between Raman probe and the analyte. And the results of quantitative analysis,based on the Raman signal intensity, will be affected. Aiming at the problem of the Raman spectral intensity, combined with multivariate analysis method based on Angle measurement, taking polyurethane prepolymer synthesis system as the research object, The on-line monitoring of percent –NCO, free TDI and-OH in polyurethane prepolymer polymerization process was studied. The main contents of this thesis are as follows:1. Summarize the principle, features and application of Raman spectral analysis technology. The multivariate analysis method based on Angle measurement, the detection methods of the percent –NCO, free TDI and-OH in polyurethane prepolymer and deficiencies of these methods was introduced2. Aiming at the problems of the traditional testing method of percent –NCO in polyurethane prepolymer, propose a novel method to fast test he percent –NCO in polyurethane prepolymer by Raman spectroscopy. Experiments used multiple prepolymer component of polyurethane paint to build calibration set, by compared a variety of pretreatment methods built by different way of pretreatment, finally get ideal percent-NCO prediction model. The prediction result is satisfactory.3. Propose an online monitoring method by Raman spectroscopy to monitoring the percent –NCO in polyurethane prepolymer polymerization process. Before regression analysis, Turn the intensity value of Raman signal to Angle measurement value by using the method of Angle measurement. thereby avoiding the influence of intensity fluctuation of Raman spectral response. The method was applied to online monitoring the percent free TDI and –OH in polyurethane prepolymer polymerization process.