Rheological Properties of Anionic Polystyrenes. II. Dynamic Viscoelasticity of Blends of Narrow-Distribution Polystyrenes

Abstract

The dynamic viscoelastic properties of broad-distribution polystyrene and blends of narrowdistribution polystyrenes have been measured in the molten state. A comparison of the frequency dependences of the storage shear modulus G', loss modulus G", and relaxation spectrum H(7) of the blends and the broaddistribution polymer with those of the narrow-distribution polymers reveals that the effect of molecular weight distribution is very marked in the terminal and rubbery zones. The log G' us. log w curve for a binary blend composed of two components having very different molecular weights manifests the "two-step" rubbery plateau, suggesting that the blend has two sets of relaxation times associated with different kinds of entanglement couplings. The zero-shear viscosity qo of the blends is almost equal to that of a narrow-distribution polymer having the same weight-average molecular weight M,, but the elasticity coefficient AG for the blends is proportional to Mw4.3, as against M7.5 for the narrow-distribution polystyrene. The steady-state compliance .leo of the blends is proportional to w2-2 when wp, the weight fraction of the high molecular weight component, is close to unity. The entanglement compliance J,NO is also approximately proportional to W Z -~, and J,NO is lower than J, O by a factor of about 3. The existence of three kinds of entanglement couplings has been pointed out, in which molecular chains of highhigh, high-low, and low-low molecular weight components are involved.any investigations of the effect of molecular weight

Viscoelastic Properties of Entangled Polymer. IV. Binary Blends of Monodisperse Homopolymers

“…CAPTIONS OF THE FiGURE S (19) for pure polystyrene components and blends , al l of which fall on the same straight line wi th a slope of 3.7.…”

The application of flow birefringence to rheological studies of polymer melts

“…Using a right handed coordinate system to define the flow, the usual convention is retained with: 1 -the flow direction; 2 -the direction of the flow gradient, and 3 -the neutral direction. If a particle in simple shear flow is given coordinates (5i.S2'53) ^^ some time time tj previous to the present time t then the present coordinate position (xj,X2,X3) reads: Xj = Si + q(t -ti) 52 (1.1-2) X2 = Zz (1.1.3) X3 -£3 (1.1.4) 1 where q is the shear rate and the macroscopic deformation is s " q(t -tj). Also present in simple shear flow is a shear stress Pi2.…”

Viscoelastic Properties of Concentrated Solutions of Poly(methyl methacrylate) in Diethyl Phthalate

“…4 The calculated values of G~N and JiN and also of Me are shown in Table VI. The value of J~N for the bulk PMMA 715, 2.15xl0-7 cm 2 / dyne, is consistent with the result reported in our previous paper, 5 which showed that the J~N was slightly dependent upon the molecular weight.…”