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

Bitumen 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.