Measurement of partial conversions during the solution copolymerization of styrene and butyl acrylate using on-line Raman spectroscopy

The copolymn. of styrene and Bu acrylate in dioxane was monitored by online Raman spectroscopy. The calcn. of the individual monomer concns. on the basis of the individual vinyl peaks is not straightforward for this system, as these bands are overlapping in the Raman spectrum. To tackle this problem, univariate and multivariate approaches were followed to obtain monomer concns. and the results were validated by ref. gas chromatog. data. In the univariate anal., linear relations between various monomer peaks were used to calc. monomer concns. from the Raman data. In principal component anal., the main variation in the spectra could be ascribed to conversion of monomer. Furthermore, principal component anal. pointed out that the second-largest effect in the spectra could be attributed to expt.-to-expt. variation, probably attributable to instrumental factors. In the multivariate partial least squares regression approach, single factor models were used to calc. monomer concns. Both the univariate and the partial least squares regression approaches proved successful in calcg. the individual monomer concns., showing very good agreement with off-line gas chromatog. data. [on SciFinder (R)