Short-range order effects in amorphous polycondensates as studied by spin polarized diffuse neutron scattering and simulation |
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Authors: | C. Lamers C. Schönfeld S. M. Shapiro J. Batoulis R. Timmermann J. W. Cable D. Richter |
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Affiliation: | (1) Present address: Forschungszentrum Jülich, Institut für Festkörperforschung, 52425 Jülich, Germany;(2) Bayer AG, Leverkusen, Germany;(3) Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA;(4) Brookhaven National Laboratory, Upton, New York, USA |
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Abstract: | Short-range order effects in amorphous polycondensates, including the technologically important bisphenol-A-polycarbonate, have been investigated by elastic diffuse neutron scattering with spin polarization analysis. Selectively deuterated samples of each polycondensate have been used in order to vary the scattering contrast and thereby emphasize different pair correlations. The technique of spin polarization analysis allowed a reliable separation of the coherent scattering and an intensity calibration on the basis of the incoherent scattering as an internal standard. Thus, (d/d)coh has been measured directly by this method. The experimental results are compared to calculated cross-sections from computer-generated structures. Simulations have been performed with the amorphous cell method which models the static structure of the amorphous polymer in full chemical detail on the basis of a random coil conformation. The results of the simulations yield a fertily ground for the discussion of the measured cross-sections, though a direct comparison with the experiment is not always satisfactory. The observed discrepancies indicate a still insufficient structural relaxation of the simulated structures.Dedicated to Professor Dr. E. W. Fischer of the occasion of his 65th birthday. |
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Keywords: | Polycarbonate partial structure factors neutron scattering simulation |
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