An FTIR standard addition method for quantification of bound styrene in its copolymers

The content of bound styrene in styrenic copolymer has a great influence on its performance. In this paper, a standard addition method for quantification of bound styrene was developed to analyze styrene/butadiene rubber (SBR), styrene-butadiene-styrene (SBS) triblock copolymer and styrene-isoprene-styrene (SIS) triblock copolymer, respectively. Polystyrene with several incremental additions was dissolved with them in chloroform separately. The obtained standard addition curve of the ratio of the absorbance at 699 cm−1 (styrene unit) to the one at 967 cm−1 (butadiene unit) or the one at 838 cm−1 (isoprene unit) versus the mass ratio of the added polystyrene to the copolymers showed good linearity (R>0.992) and accuracy (the R.S.D. for SBR, SBS and SIS was 6.38%, 3.14% and 4.07%, respectively). This developed method is universal, convenient and satisfactory.