The viscosities of concentrated polymer solutions. I. Moderately concentrated solutions

Abstract

The enormous increases of the viscosity, η, and the associated activation heat, Qη, in concentrated polymer solutions are attributed to the formation of intermolecular linkages between high polymer molecules and to the increase of glass transition temperature with increasing concentration of the solution. In this paper, the effects of the intermolecular linkages on the viscosity of moderately concentrated solutions were discussed. In this concentration range, η and Qη are represented by unique functions of reduced concentration, vR = BMv2, and the following equation was derived for Qη; Here M is the molecular weight of the polymer, v2 is the volume fraction of the polymer, ΔE is the energy to form an intermolecular linkage, B is a constant for the solution, and Qη0 is the activation heat of viscosity for the solvent. The dependency of η on vR shifts from a first power proportionality to a third power at vR = 1/2. The theory was compared with experiments for solutions of cellulose tributyrate in trichloropropane, polyvinyl alcohol in water, polyvinyl acetate in acetone, and polyisobutylene in xylene.

Theory of viscoelastic behaviour of linear polymers in unimolecular approximation and its experimental verification

“…which is only slightly different from formula [29]. The above-mentioned physical meaning of the constant g is thus confirmed.…”

“…It should be noted that in our calculations the value of the activation energy of formation of entanglements was assumed to be equal to 2 kcal/mole according to the data by Hirai (29). The estimation carried out for the data presented in fig.…”

“…Note that if expressions [26] and [27] apply to polymer melts and concentrated solutions, then from analysis of experimental facts (3) it follows that E m Ee ~0~e T and g 1~ c2eT [30] where Em-activation energy of viscous flow of a monomer liquid kcal/mole; Ee-activation energy of entanglement formation which does not exceed 2-5 kcM/mole (29).…”

Cryostructuring of Polymeric Systems. 49. Unexpected “Kosmotropic-Like” Impact of Organic Chaotropes on Freeze–Thaw-Induced Gelation of PVA in DMSO

“…It was expected that the values of the intrinsic viscosity and the Huggins constant will allow one to reveal the influence of URE on the hydrodynamic characteristics of the PVA macromolecules in dilute polymer solutions and evaluate the affinity of PVA to these solvents for at least two temperatures. In turn, the temperature dependences of the viscosity of the moderately concentrated (in terms of the Hirai concept [63]) PVA–DMSO solutions in the absence and presence of URE allowed a rough evaluation of the PVA self-association energetics. The hydrodynamic and thermodynamic parameters of PVA in these solvents are listed in Table 1.…”

Relative viscosity and concentration

“…Hirai (135) proposed such a function for moderately concentrated polymer solutions of 5-20 weight/volumeO/o, reckoning with intermolecular linkages. He introduced a reduced concentration, c R = B.M-e, M being molecular weight and B a factor depending on energy and entropy of the linkage formation, thus varying with the system.…”