Nonlinear phase-separation behavior of poly(methyl methacrylate)/poly(styrene-co -maleic anhydride) blends

Abstract

The nonlinear phase-separation behavior of poly(methyl methacrylate)/poly(styrene-co-maleic anhydride) (PMMA/SMA) blends over wide appropriate temperature and heating rate ranges was studied using time-resolved small-angle laser light scattering. During the non-isothermal process, a quantitative logarithm function was established to describe the relationship between cloud point (Tc) and heating rate (k) as given by Tc = Alnk + T0, in which the parameter A, reflecting the heating rate dependence, is much different for different compositions due to phase-separation rate and activation energy difference. For the isothermal phase-separation process, an Arrhenius-like equation was successfully applied to describe the temperature dependence of the apparent diffusion coefficient (Dapp) and the relaxation time (τ) of the early stage as well as the late stage of spinodal decomposition (SD) of PMMA/SMA blends. Based on the successful application of the Arrhenius-like equation, the related activation energies could be obtained from Dapp and τ of the early and late stages of SD, respectively. In addition, these results indicate that it is possible to predict the temperature dependence of the phase-separation behavior of binary polymer mixtures during isothermal annealing over a range of 100 °C above the glass transition temperature using the Arrhenius-like equation. © 2012 Society of Chemical Industry