Viscoelastic effects on the dynamics of spinodal decomposition in binary polymer mixtures

Numerical simulations based on the modified time-dependent Ginzburg-Landau (TDGL) equation have been performed on the domain growth dynamics of binary polymer mixtures. An elastic relaxation term was introduced into the equat ion to take the entanglement effects of the polymer chains into account. A cell dynamical scheme (CDS) is employed in this paper to improve the comput ing efficiency. The dynamics of the phase separation in polymer blends was investigated through to a very late stage. In the system without viscoelast ic effects, there exists an apparent early stage, and in the late stage the modified Lifshitz-Slyozov law and dynamical scaling law are satisfied very well. In the system with viscoelastic effects, there are some unique chara cteristics. A morphology with a rough interface between the domains is obta ined and suppression of order-parameter fluctuations is observed. The growt h behavior of domains was altered, and there exits an intermediate stage be tween the early and late stage, in which the growth rate of domains slows d own drastically. The intermediate stage was prolonged with enhanced entangl ement effects. Entanglement effects also enhance the quench-depth effects o n the correlation and diminish the discrimination of correlation induced by : criticality. After the relaxation of entanglements, the, growth exponent s with the model employed in this paper are independent of entanglements an d are essentially consistent with the modified Lifshitz-Slyozov law. In add ition, the pair correlation function and the structure function are shown t o exhibit the dynamical scaling law at the late stage.