Wavevector dependence of the initial decay rate of fluctuations in the polymer solutions.

We present experimental results for the initial decay rate gamma(1) of concentration fluctuations in solutions of linear polymers, for various molecular weights, concentrations and wavevectors q, in two rather different solvents. We find that under all conditions explored the dimensionless decay rate 6pieta(omicron)gamma(1)/kappa(beta)tau (q)(3) is a function only of the scaled wavevector qxieta. Here eta(omicron) is the solvent viscosity, and xi(eta) is the length scale defined by xiH/-1=lim (omicron)-6pieta(omicron)gamma(1)/(kapp(beta)tau (q)(2)).