SCATTERED INTENSITY BY A CROSS-LINKED POLYMER BLEND

Cross-linked mixtures of polystyrene and poly(vinyl methyl ether) exhi bit a non-vanishing zero-angle intensity in small-angle neutron scatte ring experiments. a possible explanation is that fluctuations in compo sition in the mixture may be frozen by the presence of cross-links. As suming this, we introduce a screening length kappa by the condition th at the scattered intensity should not be changed by cross-linking. We find kappa(2) similar to C/((chi-chi i)), where C is an elastic consta nt, (chi) and (chi i), respectively, the inverse temperature and that where cross-linking is performed. When the temperature is varied, we f ind three regimes. In the first one, the scattered intensity is monoto nously decreasing. In the second one, it has a finite maximum. In the last one, the maximum eventually diverges.