How good is the bead-spring model?

Abstract The predictions of the bead-spring model are compared with the infinite dilution dynamic properties of polystyrene in Aroclor 1248, as a function of molecular weight. The experimentally determined quantities include the longest relaxation time and the relaxation-time spectrum, obtained via oscillatory flow birefringence; the diffusion coefficient, measured by NMR and forced Rayleigh scattering; the radius of gyration, determined by small-angle neutron scattering; and the intrinsic viscosity. In all cases, the data are very well described by the model, using a consistent set of three parameters. However, the conformational dynamics experiments suggest a surprisingly sharp end to the relaxation spectrum, corresponding to the relaxation time for an approximately 50-monomer subchain.