SCATTERED INTENSITY BY A CROSS-LINKED POLYMER BLEND

Cross-linked mixtures of polystyrene and poly(vinyl methyl ether) exhibit a non-vanishing zero-angle intensity in small-angle neutron scattering experiments. a possible explanation is that fluctuations in composition in the mixture may be frozen by the presence of cross-links. Assuming this, we introduce a screening length kappa by the condition that 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 constant, (chi) and (chi i), respectively, the inverse temperature and that where cross-linking is performed. When the temperature is varied, we find three regimes. In the first one, the scattered intensity is monotonously decreasing. In the second one, it has a finite maximum. In the last one, the maximum eventually diverges.