In Line And In Situ Monitoring Of Emulsion Copolymerization Using Near-Infrared Spectroscopy

Emulsion product is widely applied in many fields, but there is not an effective method to measure the emulsion system fast in emulsion polymerization industry. We really need the method to monitor reactor. Near-infrared spectroscopy technology could help to measure emulsion system in-line, based on the advantage of fast and in-line measurement.The styrene / butyl acrylate emulsion copolymerization was researched in this thesis. The absorbance near-infrared spectroscopy was measured by transmission- reflection probe in reactor every 10 min, and the emulsion sample was got at the same time. We got the properties of emulsion sample, they were residual monomer concentration, particle size, polymer concentration, molecular weight of polymer, St mol percentage in copolymer of it, through the method of Gas Chromatogram (GC), Dynamic light scattering (DLS), drying, Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (H~1-NMR). The calibration models of these properties were established by the method of multiplicative correction. The result shows that it is feasible for near-infrared spectroscopy technology to measure the property of emulsion system in-line. Based on the coefficient of square correlation (R~2) and standard error of calibration (SEC) between the actual value and predicted value, the calibration models were optimized. Emulsion system is composed of emulsion particle, so the near-infrared could be scattered by the particle. It is discovered that the Multiplicative Scatter Correction (MSC) is effective to improve the ratio of information and noise, and overcame the influence of scattered near-infrared information. And the scattered near-infrared information is quite useful for particle size calibration model. There is correlation between them.The residual monomer concentration was measured by the calibration model in-line, and the consecutive data of residual monomer concentration was got in emulsion polymerization. The regularity is consistent with the emulsion polymerization theory. Besides, by some different ways, the reactivity ratio was calculated though consecutive data of residual monomer concentration.