Novel Characterization of Block Styrene in Poly(styrene-co-butadiene)

Tire performance using solution poly(styrene-co-butadiene), SBR, continues to be enhanced with the development of new polymerization technology and the advancement of materials science. The controlled incorporation of styrene monomers into the elastomer backbone in short 3-10 unit blocks (microblocks) has been an important contribution. However, a timely manner to quantify these blocks was needed. ¹HNMR analysis is a traditional way of determining the microblock styrene content in SBR but it is not a convenient way to make such a measurement because of the cost and time restrictions needed for the commercial production. On the other hand Pyrolysis-GC-FID technique is both fast and available at the production facilities. Preferred pyrolysis conditions were identified as 700°C for 6s to generate sufficient amount of styrene monomer, dimer and trimer from the copolymers for this measurement. A novel data analysis technique was developed to determine microblock styrene from the pyrolysis-GC-FID data. The statistical data analysis method is based on the relative amount of the styrene monomer, dimer and trimer. Accuracy of the method was compared to the traditional NMR technique and the cross correlation r²was found to be 0.94. The method is easily automated to the production environment.