Viscosity–temperature relationships for linear and 12‐arm star polystyrenes in dilute solution

The actual viscosities (cP) of dilute solutions of linear and 12‐arm star polystyrenes were measured in benzene, a good solvent, and cyclohexane, a poor to moderate solvent, as a function of temperature. The equations of Moore, previously established for solutions of linear polymers, were also found to be valid for star polystyrenes. A branching parameter b was defined which is essentially the same as g′ = [η]_br/[η]₁. The values of b found in benzene are close to the value of g′ for 12‐arm star polystyrene in toluene, another thermodynamically good solvent. It thus appears that Moore's relationships have at least limited utility in studying branching in polymers.