Viscoelastic and Fracture Phase Separation induced under different quench depths at critical composition

The influence of different quench depths on the morphology of polystyrene (PS)/ poly(vinyl methyl ether) (PVME) blends in unstable and metastable region has been investigated using optical microscopy and dynamic rheology techniques. Typical SD morphology disappeared under large quench depths; some specification might control the morphological evolution. For PS/PVME (30/70) blend at different quench depth, the formation of a network structure and subsequent the phase inversion indicates that a transition from spinodal decomposition (SD) to typical viscoelastic phase separation (VPS) has been occurred. Furthermore, the morphology is changed to fracture phase separation (FPS) at high quench depth. The rheological relaxation time suggests that the observed morphology transition was related to the change in the dynamic asymmetry between the PS-rich phase and the PVME-rich phase

Keywords:

Dynamic asymmetry , Viscoelastic phase separation , Fracture phase separation