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Flow relationships at high shear in concentrated polyisobutene solutions
Author(s) -
Porter Roger S.,
Johnson Julian F.
Publication year - 1960
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1960.070030715
Subject(s) - shear rate , viscometer , shear (geology) , polymer , shear stress , laminar flow , chemistry , materials science , thermodynamics , shear flow , viscosity , analytical chemistry (journal) , composite material , chromatography , physics
A concentric cylinder viscometer was used to measure high shear viscosities of polyisobutene solutions. Data were obtained in laminar flow from 20–100°C. and at shear rates from 5 × 10 2 to 8 × 10 5 sec. −1 . Three polymer molecular weights, 4.0 × 10 4 −2.2 × 10 6 , in three concentrations from 11.5–49.2 wt.‐% polymer were tested in cetane. The viscosity of cetane at all test temperatures was low and independent of shear rate up to 10 6 sec. −1 . Therefore, variations in viscosity with shear were due totally to the effect of polymer. Viscosities of 11.5% solutions of low molecular weight polyisobutene, 4–6 × 10 4 , approached limiting viscosities at both high and low rates of shear. Viscosity changed markedly between the limiting values as did the flow activation energy at constant shear rate, Δ E * r . At extremes of both high and low shear rate Δ E * rappeared to be insensitive to polymer molecular weight. Solutions containing the highest molecular weight and concentration of polyisobutene reached shear stresses for polymer degradation before a limiting high shear viscosity could be observed. For all solutions, Δ E * rwas independent of temperature form 20–100°C. At low shear, Δ E * rincreased with polymer concentration. At high shear, the concentration dependence was reversed, with the highest concentration having the lowest Δ E * r . A simple shear correlation was found to superimpose all data for which reduced viscosities could be derived. Reduced specific viscosities superimposed on a master curve when plotted against log (shear stress/ T°K ). The correlation covered data at all temperatures and concentrations for the two lower molecular weight polymer solutions.