Rapid FTIR method for quantification of styrene-butadiene type copolymers in bitumen

The mid-IR molar absorptivity for polystyrene (PS) and polybutadiene (PB) b locks were obtained for five styrene-butadiene-styrene (SBS) and SE copolym ers, including linear, branched, and star copolymers, and their blends with bitumen. The average absorptivity for PS and PB blocks was 277 and 69 L mo l(-1) cm(-1) and it was little affected by the S/B ratio or the copolymer a rchitecture. In the presence of bitumen, Beer's law was obeyed but the resp ective PS and PE absorptivity was 242 and 68 L mol(-1) cm(-1), possibly bec ause of weak interactions between the copolymer and bitumen. The absorptivi ty values were used to calculate the concentration of SE-type copolymers in blends with bitumen with an accuracy of 10% or better. The method can be u sed to probe the stability of bitumen-copolymer blends in storage at 165 de greesC, to determine the copolymer concentration in commercial polymer modi fied bitumen (PMB), and to assess the resistance of PMB to weathering. (C) 2000 John Wiley & Sons, Inc.