Late stage spinodal decomposition in an oligomeric blend of polystyrene/polybutadiene: A test of the scaling law for the structure function

摘要

The late stages of phase separation by spinodal decomposition have been studied by light scattering in an oligomeric blend of polystyrene (PS) with polybutadiene (PB) as a function of both quench depth and composition. The scattering functionI(q,t) follows a dynamical scaling law of the formS(q,t)=qm(t)minus;3Stilde;lsqb;q/qm(t)rsqb; where the wave vectorqmcorresponds to the maximum inI(q,t). The profiles of the normalized scaled structure functions are compared with that predicted by Furukawa for critical mixtures (percolation regime) which is given byStilde;(x)=4x2/(3+x8)lsqb;Stilde;(1)=1rsqb;. Apart from one exception, Furukawarsquo;s function adequately describes the form of the normalized structure functions for a 60percnt; PS mixture. However there are problems with some of the comparisons with the 50percnt; and 70percnt; PS blends. These disparities may in part be attributable to the fact that some of the data may lie outside the lsquo;lsquo;truersquo;rsquo; late stages.