Small-angle x-ray scattering experiments for investigating the validity of the two-phase model

Abstract

A New method for evaluating SAXS curves of polymer samples with lamellar structure is applied to two typical scattering curves measured with a solution-crystallized linear polyethylene and a melt-crystallized branched polyethylene respectively. The method permits a rigorous check of the validity of the two-phase model and yields, without additional measurement, the volume fractions of the two phases and the difference in their densities. The densities can than be obtained by measuring the overall density of the sample. The results are: ρ_c = 0.996 g/cm³, ρ_a = 0.854 g/cm³, w_a = 0.20 for the solution-crystallized sample; ρ_c = 0.967 g/cm³, ρ_a = 0.850 g/cm³, w_a = 0.36 for the melt-crystallized sample.