ISO 21561-2:2024

This document specifies procedures for the quantitative determination of the microstructure of the butadiene portion and the content of styrene in solution-polymerized SBR (S-SBR) by Fourier transform infrared spectrometry (FTIR) with attenuated total reflection (ATR) method. The styrene content is expressed in mass fraction relative to the S-SBR. The contents of three microstructure types, i.e. vinyl, trans and cis, are expressed in mol fraction relative to the butadiene portion in the S-SBR. This method is only applicable to raw rubbers. NOTE 1       Precision as shown in Annex A is not always possible to obtain for S-SBRs containing polystyrene block or styrene content more than 45 %. NOTE 2       Only “vinyl”, “trans” and “cis”, are used in this document. However, the expression of vinyl, trans and cis mean as follows in general: —      vinyl: vinyl unit, vinyl bond, 1,2-unit, 1,2-bond, 1,2-vinyl-unit or 1,2-vinyl-bond; —      trans: 1,4-trans unit, 1,4-trans bond, trans-1,4 unit or trans1,4 bond; —      cis: 1,4-cis unit, 1,4-cis bond, cis-1,4 unit or cis-1,4 bond.