Viscoelasticity and self-diffusion in melts of entangled linear polymers

✍ Scribed by Carol B. Gell; William W. Graessley; Lewis J. Fetters

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 243 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19970915)35:12<1933::aid-polb8>3.0.co;2-q

✦ Synopsis

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 h 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 h 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 h o D/(h o D) Rouse is a universal function of the number of entanglements per molecule M/M e . With values for 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.