Study of entanglement of polymers in solution by viscosity measurements. II. Polymethyl methacrylate in various solvents

A study has been made of the flow behavior at 30°C. of solutions of three samples of polymethyl methacrylate in three solvents in both the Newtonian and non‐Newtonian regions. The concentration range covered was approximately 0–16% by weight. By application of the Ree‐Eyring theory it was found possible to represent the observed data in terms of two flow units, and to obtain from the parameters of the theory the effective hydrodynamic volume occupied by the polymer in solution, ευ2. Here υ2 is the volume fraction of the polymer and ε an effective volume factor. The volume factor, ε, was found to be dependent on both solvent and molecular weight only up to ca. υ2 = 0.04. Beyond υ2 = 0.04, ε is independent of solvent and is a function of molecular weight only. These observations indicate that chain entanglement in solution is not probable. Rather, the polymer chain curls on itself, and compacts to a small mass when the effective concentration ευ2 = 1 and the viscosity becomes infinite. The concentration at which this occurs, υ∞, is given by ∞ = 1/ε∞. The quantity ε∞ has been found to be a linear function of molecular weight, M. Further, the value of ε at υ2 = 0, ε0, has been found to be an exponential function of M, and to yield expressions relating intrinsic viscosity to molecular weight in good accord with published results.