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SUMMARYUsing a Langevin-like approach, the deformation of a polymer, modelled as a bead-spring chain, is calculated in simple shear, elongational and Kramers potential flow. Analytic expressions for the mean-square end-to-end distance, radius of gyration, segment-segment distance, static structure factor up to O ( q 4 ) and the intrinsic elongational viscosity are given. Near equilibrium, preaveraged hydrodynamic interaction is taken into account.

SUMMARY:We present a study of various properties of bead spring chains in steady flows. The Langevin equation of the normal modes of the chain is solved by Fourier transformation. From the resulting power spectrum, the autocorrelation functions of all configurationdependent quantities can be calculated. In equilibrium, the influence of the bead masses on the short-time dynamics is discussed. The influence of different flow fields (shear, elongational and Kramers potential flow) on the mean-square chain dimension is calculated. A comparison with results obtained from non-equilibrium molecular dynamics and Monte Carlo calculations is made. Finally, the influence of shear flow on the configurational and rheological properties of cyclic polymers and on the excluded volume behaviour of linear chains is examined.

SUMMARY:A simple model for the calculation of configurational and rheological properties of finitely extensible polymers in flow is introduced. The finite extensibility of the chain is incorporated into the common Rouse model by varying the spring constant such that a constant contour length is maintained for every flow strength. For elongational flow, a comparison with Monte Carlo simulations of a bead-rod chain with 100 links yields qualitative agreement. For shear flow, this model predicts non-Newtonian flow behaviour.

The configurational and rheological properties of multiple-twisted ring polymers, modelled as long cyclic finitely extensible bead-spring chains with internal distance constraints, have been calculated. This model corresponds to chemically cross-linked Rouse chains. The calculations were carried out for equilibrium and steady shear flow. The mean-square radius of gyration in equilibrium depends on the number of loops. In shear flow, non-Newtonian flow behaviour arises. The shear viscosity and the first normal stress coefficient decrease with increasing shear rate. The second normal stress coefficient is negative and much smaller than the first normal stress coefficient. Since the mean-square radius of gyration, shear viscosity and the first and second normal stress coefficients depend on the number of loops, the latter can be determined by four independent experiments.