SHORT-RANGE ORDER EFFECTS IN AMORPHOUS POLYCONDENSATES AS STUDIED BY SPIN-POLARIZED DIFFUSE NEUTRON-SCATTERING AND SIMULATION

Short-range order effects in amorphous polycondensates, including the technologically important bisphenol-A-polycarbonate, have been investi gated by elastic diffuse neutron scattering with spin polarization ana lysis. Selectively deuterated samples of each polycondensate have been used in order to vary the scattering contrast and thereby emphasize d ifferent pair correlations. The technique of spin polarization analysi s allowed a reliable separation of the coherent scattering and an inte nsity calibration on the basis of the incoherent scattering as an inte rnal standard. Thus, (d sigma/d Omega)(coh) has been measured directly by this method. The experimental results are compared to calculated c ross-sections from computer-generated structures. Simulations have bee n performed with the ''amorphous cell'' method which models the static structure of the amorphous polymer in full chemical detail on the bas is of a ''random coil'' conformation. The results of the simulations y ield a fertile ground for the discussion of the measured cross-section s, though a direct comparison with the experiment is not always satisf actory. The observed discrepancies indicate a still insufficient struc tural relaxation of the simulated structures.