Effect of the thermal degradation of SBS copolymers during the ageing of modified asphalts

The change in the properties of the styrene–butadiene block copolymers (SBS) modified asphalt under different ageing conditions has been studied. Normalized test and rotational viscosities show the effect of the degradation and the modification of the polymer–asphalt interactions with the severity of the ageing. Using size exclusion chromatography and infrared spectroscopy the effect of the different molecular weight and architecture of the chosen SBS during the thermo-oxidative degradation has been determined. The main products of this process were low molecular weight polymers from chain scission and reaction products coming from polymeric radical–asphalt reactions. Hence, the resulting structural modifications may explain the physical and rheological properties of asphalt during the ageing.