Spinodal Decomposition in Polymeric Systems

Abstract

A temperature-dependent statistical theory of two-and three-spin cross relaxation processes is developed for S = 1 paramagnetic ions. It takes account of fluctuations of magnetic quantum numbers of the ions due to spin-spin and spin-lattice interactions in terms of the ensemble theory of statistical mechanics. Explicit two-and three-spin resonant cross relaxation rates are computed for Ni2+ ions in the diamagnetic host lattice of dioxane and compared with experimental results. Reasonably good agreement is obtained with experiment, both with regard to temperature dependence and the actual magnitudes of two-and three-spin cross relaxation rates.

Front migration in the nonlinear Cahn-Hilliard equation

“…Experimental investigation of the validity of the Cahn-Hilliard equation has been largely limited to the early-time linear regime, where long-wavelength and perturbations of a homogeneous unstable state grow exponentially and equation (1.3) may be solved analytically. Recent surveys are given by Skripov & Skripov (1979), Gunton & Droz (1983), Lipatov & Shilov (1984) and Nose (1987). The linear Cahn-Hilliard equation has been quantitatively validated only rarely, however, for various reasons, including the short time of validity of the linear regime, too-large initial fluctuations, and other relevant dynamic effects such as thermal noise, coherency strain and coupling to other slow variables.…”

Phase-Separated Interpenetrating Polymer Networks

“…The possibility of another mechanism of phase separation in IPNs, spinodal decomposition, was discovered in 1984-1985 [5,53,[82][83][84][85][86][87][88]. Studying various semi-and full IPNs we have discovered that the microheterogeneous structure of IPNs arises as a result of microphase separation proceeding according to the spinodal mechanism of phase separation.…”