Mean-field Ising crossover and the critical exponents γ, ν, and η for a polymer blend:d-PB/PS studied by small-angle neutron scattering

The critical behavior of the polymer blend d-PB/PS was investigated by small-angle neutron scattering experiments. 3D Ising behavior was clearly observed with the critical exponents γ=1.26±0.01, ν=0.59±0.01, and η=0.047±0.004. The crossover to mean-field behavior occurs at ${\mathit{T}}^{\mathrm{*}}$=${\mathit{T}}_{\mathit{c}}$+5.4 K. This is compared with the results of other experiments and the Landau-Ginzburg criterion. The Q dependence of the structure factor S(Q) follows the Ornstein-Zernike form in both regimes.