Phase-Destabilization Mechanism of Polymer-Modified Bitumens ‎in Quiescent Annealing

B itumen as a binder in coating and ‎insulating materials is modified ‎with polymers to improve its ‎performance in service conditions. ‎Almost all polymers are ‎incompatible with bitumen, and at ‎high temperatures due to relatively ‎very low viscosity of the bitumen ‎phase, are separated from it. These ‎lead to a considerable limitation in ‎the use and handling of polymer-‎modified bitumens. An ‎understanding of the mechanisms ‎of phase separation of these ‎incompatible mixtures help to ‎improve methods of transportation ‎and handling of polymer-modified ‎bitumens. According to direct ‎observations of the behavior of ‎polyethylene particles in medium ‎of molten bitumen confirm the ‎indirect conclusion already made ‎by others, (coalescence based ‎phase separation) and reject any ‎possibility of occurring Ostwald ‎ripening. This conclusion can also ‎generalized to viscoelastic ‎incompatible polymer blends. ‎