Av. Bazilevskii et al., Breakup of an Oldroyd liquid bridge as a method for testing the rheological properties of polymer solutions, POLYM SCI A, 43(7), 2001, pp. 716-726
The rheological properties of polymer solutions were studied by monitoring
the breakup of the liquid bridge (thinning filament). The behavior of the l
iquid subjected to a deformation in a bridge (filament) was modeled by the
Oldroyd general equation of state, which takes into account nonlinear effec
ts, finite extension limit, and a spectrum of relaxation times. A procedure
and a corresponding algorithm were developed for determining rheological c
onstants from experimental data on the time dependence of the filament diam
eter. The thinning of filaments of polymer solutions with various viscositi
es of the solvent were experimentally studied. Solutions of poly(acrylamide
) with M = 1.1 x 10(7) were studied in the concentration range from 0.5 to
30000 ppm. The solvents were water and water-glycerin mixtures. It was esta
blished that the rheological behavior of the liquids under study is closely
described by the Oldroyd model with a single relaxation time. The dependen
ces of the relaxation time and modulus of elasticity on the concentration o
f polymer and on the solvent viscosity were obtained. The experimental data
were found to contradict the predictions of the molecular-kinetic theory o
f polymer solutions.