Viscoelastic properties of branched polymers. I. At the undiluted state.

The viscoelastic properties of four-armed, star-shaped polystyrenes having narrow molecular weight distributions were studied in a undiluted state by the tensile stress relaxation method. The steady-flow viscosity, the steady-state compliance and other rheological parameters were determined from the relaxation modulus master curves. The molecular weight dependences of these parameters were compared with those of linear and comb-shaped polymers.