Towards the development of a viscoelastic model for phase separation in polymer-modified bitumen

The development of a viscoelastic model for phase separation in polymer-modified bitumen (PMB) is proposed in this paper. PMB is considered as a pseudo-binary blend. Equilibrium thermodynamics and phase separation dynamics of PMB are discussed. The effects of dynamic asymmetry on phase separation in PMB are analysed with related theories and some image data. Based on the discussion in this paper, it is concluded that the effects of dynamic asymmetry between bitumen and polymer should be taken into consideration when studying phase separation in PMB. By analysing related literature and image data, it is found that some features of viscoelastic phase separation are shown during the phase separation process in some PMBs. It is possible to develop a viscoelastic model for PMB to describe its phase separation behaviour. The stress–diffusion coupling would play a key role in the model by introducing composition-dependant mobility, shear and bulk stress.