ESTIMATING COPOLYMER COMPOSITIONS FROM ONLINE HEADSPACE ANALYSIS IN EMULSION POLYMERIZATION

An improved methodology has been studied for the calculation of instantaneous copolymer compositions that occur during batch emulsion polymerization of monomers exhibiting partial water solubility, as in the case of styrene and acrylonitrile. To achieve this, a newly designed chromatographic probe installed in the reactor gas space is operated periodically. To accurately relate vapor compositions to copolymer compositions, the parameters that define the multiple phase equilibria (liquid-liquid vapor) and the reactivity ratios must be obtained in separate experiments. Thus, liquid-liquid distribution coefficients, as well as monomer activity coefficients and reactivities, were experimentally determined.