The Effect of Entanglements on Viscoelastic Properties of Carbohydrate Pastes

Abstract

The dynamic properties of concentrated polymer solutions have been investigated by taking into consideration the effect of deforming entanglement networks.According to the Hayashi theory, there exists the box type region of relaxation spectrum due to the entanglement of polymer chains in the relaxation time region which is longer than the wedge type region corresponding to the mechanism described in the Rouse-Zimm theory.The viscoelastic properties of polymer solutions are affected by the molecular weight distributions of solute (polymer), so that the molecular weight distribution should be taken into consideration in calculation of the relaxation spectrum. (In this paper), it is assumed that the relaxation spectrum is based on the Hayashi theory that the effects of the molecular weight distribution are to be calculated by the Ninomiya-Fujita method, and so we have computed the complex modulus G' and G" for the values of entanglement density as function of angular frequency. Comparing these curves, theoretical and experimental, the following conclusions have been obtained.(1) As for the polyisoprene-toluene system which follows the M3.4 law of viscosity, the experimental curves of its complex modulus approximately agree with the theoretical curves.(2) As for the Alg-aqueous solution, in spite of the fact that its viscosity is far more dependent on its molecular weight than it is the case with the polyisoprene-toluene system, and so the agreement of curves in its case between the experimental and the theoretical is short of being complete, the theoretical curves have been corrected to such extent, by taking into consideration the extreme degree of the dependence of its viscosity on its molecular weight, as to make the theoretical curves practically agree with the experimental curves.