Laboratory investigation of epoxy asphalt binder modified by brominated SBS

Abstract

Brominated styrene–butadienestyrene triblock copolymer (BrSBS) is a novel polymeric flame retardant (PolyFR), which is eco-friendly due to its huge molecule weight. In this paper, BrSBS was added into an epoxy asphalt binder (EAB) to enhance the flame resistance of EAB. The microstructure, viscosity, fire resistance, thermal stability, dynamic mechanical behaviors and mechanical properties of BrSBS modified EABs (EBrSAs) were studied. Double phase separation occurred in EBrSAs. BrSBS modified asphalt (BrSA)-rich phase co-continuously dispersed in the continuous epoxy matrix when BrSBS content was lower. However, phase-inverted morphology appeared when the BrSBS content was higher. In other words, the epoxy-rich phase dispersed in the continuous BrSA-rich phase. The amine curing agent reacted with BrSBS through a bimolecular nucleophilic substitution (S_N2) mechanism, resulting in the formation of epoxy/BrSBS interpenetrating polymer networks (IPNs). The incorporation of BrSBS greatly increased the viscosity of the neat EAB due to the nucleophilic substitution reaction between BrSBS and amine curing agent. BrSBS with lower loading significantly improved the flame retardancy of the neat EAB. BrSBS lowered the thermal stability, mechanical and damping behaviors of the neat EAB. However, the glass transition temperature (T_g) of the neat EAB was notably enhanced with the inclusion of BrSBS.