DYNAMIC SCALING OF THE STRUCTURE-FUNCTION FOR SPINODAL DECOMPOSITION IN CRITICAL AND NONCRITICAL MIXTURES OF POLY(VINYL ACETATE) POLY(METHYL METHACRYLATE)

The dynamics of phase separation in a binary polymer blend of poly(vin yl acetate) with poly(methyl methacrylate) was investigated by using a time-resolved light-scattering technique. In the later stages of spin odal decomposition, a simple dynamic scaling law was found for the sca ttering function S(q, t)(S(q, t) approximately I(q, t)): S(q, t)q(m)-3 S approximately (q/q(m)). The scaling function determined experimenta lly was in good agreement with that predicted by Furukawa, S approxima tely (X) approximately X2/(3 + X8) for critical concentration, and app roximately in agreement with that predicted by Furukawa, S approximate ly (X) approximately X2/(3 + X6) for non-critical mixtures. The light- scattering invariant shows that the later stages of the spinodal decom position were undergoing domain ripening.