Journal of Polymer Science Part B: Polymer Physics, Vol.35, No.12, 1933-1942, 1997
Viscoelasticity and Self-Diffusion in Melts of Entangled Linear-Polymers
Dynamic properties in the melt state for two saturated hydrocarbon polymers, poly( ethylene-alt-propylene) (PEP) and head-to-head polypropylene (HHPP), were investigated by viscoelastic and diffusion measurements, Several nearly monodisperse linear samples of each species were used. Zero-shear viscosity eta(o) and self-diffusion coefficient D varied with temperature in accord with the WLF equation, and they also varied with molecular weight M in a manner that was consistent with the behavior of other species. The product eta(o)D was of particular interest because extensive previous results for two other species, polystyrene and polyethylene, had led Pearson et al. to suggest that eta(o)D/(eta(o)D)(Rouse) is a universal function of the number of entanglements per molecule M/M-e. With values far the Rouse model product for each species calculated from chain dimensions, and entanglement molecular weight from the plateau modulus, we show that the data for PEP and HHPP also support the Pearson universal form.
Keywords:HYDROCARBON POLYMERS;HYDROGENATED POLYBUTADIENE;MOLECULAR-WEIGHT;COEFFICIENT;VISCOSITY;BLENDS