Dependence of the Zero Shear Melt Viscosity and the Related Friction Coefficient and Critical Chain Length on Measurable Characteristics of Chain Polymers

Available η—Z—T data for a wide variety of well defined linear and branched polymers and polymer—diluent mixtures are well represented by the single equation η=4.8×108(X/4.7×10—15)αζ , α=3.4 for X≥4.7×10—15, α=1.0 for X≤4.7×10—15. Here X=(〈s02〉Av/va)φ1, where 〈s02〉Av is the unperturbed mean-square radius of gyration of the macromolecule, va the volume per chain atom, and φ1 the volume fraction of polymer; values of the friction factor per chain atom ζ, computed from viscosity data by this equation, agree with independently determined values in the literature. This result confirms Bueche's theory for the viscosity of short chains and supports his theory for the viscosity of long chain macromolecules. An attempt to reduce ζ-T data for different systems to a single curve by introduction into the WLF equation of the term E/RT, where E may be related to the rotational barriers within the chain, is also presented.