Determination of polybutadiene microstructures and styrene-butadiene copolymers composition by vibrational techniques combined with chemometric treatment

Vibrational spectroscopy techniques have been used to study the polymer com position using only one technique at a time. In this paper, mid- and near-i nfrared (NIR) as well as Raman spectroscopies are combined with partial lea st squares (PLS) in order to determine the cis-, trans- and vinyl-configura tions of polybutadienes as well as the composition of styrene-butadiene cop olymers. A critical comparison of these techniques for the microstructure a nalysis will also be presented not only in terms of quantitative results bu t also in the way the samples can be analyzed and the spectra interpreted. Each of the techniques gives comparable results in terms of the precision o f the models developed (limited to the precision of the reference method), but we can also sec that the NIR spectroscopy is more reproducible in the s hort term due to the high signal to noise ratio obtained on the spectra. On the other hand, Raman excited in the NIR (FT-Raman) is the only technique which is free of sample preparation and handling allowing to get very good results in the long term. (C) 2001 Elsevier Science B.V. All rights reserve d.