scholarly journals Effects of Molecular Weight Distribution on the Linear Viscoelastic Properties of Amorphour Linear Polymers in the Rubbery Region

1960 ◽  
Vol 9 (76) ◽  
pp. 8-11
Author(s):  
K. Ninomiya
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Viscoelastic Properties ◽  
Linear Polymers ◽  
Linear Viscoelastic

Peculiarities of flow and viscoelastic properties of solutions of polymers with a narrow molecular-weight distribution

1973 ◽  
Vol 9 (11) ◽  
pp. 1231-1249 ◽  
Author(s):  
G.V. Vinogradov ◽  
A.Ya. Malkin ◽  
N.K. Blinova ◽  
S.I. Sergeyenkov ◽  
M.P. Zabugina ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Viscoelastic Properties ◽  
Narrow Molecular Weight Distribution

Viscoelastic Characterization of Long Branching and Gel in Butadiene-Acrylonitrile Copolymer Elastomers

1980 ◽  
Vol 53 (1) ◽  
pp. 14-26 ◽  
Author(s):  
N. Nakajima ◽  
E. R. Harrell
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
General Rule ◽  
The Other ◽  
Model Systems ◽  
Newtonian Flow ◽  
Long Chain Branching ◽  
Linear Viscoelastic ◽  
Definition Of

Abstract Difficulties in relating long-chain branching to processability may be attributable to two causes: one is the definition, pertinent to processability, of what long branches are and the other is a method of determining long branching which is free from interference by other material variables, such as molecular weight distribution, gel, and “short” branches. Measurements of the dilute solution properties are tedious, time-consuming, and require skill for precision. In addition, the requirement for filtering the solution practically obliterates the result, regardless of how precise the measurement may be, because elastomers, as a general rule, have or are suspected to have an insoluble gel fraction. Recent advances in viscoelastic studies of model polymers show that the branches must be 2–3 times longer than the “entanglement coupling” distance in order to exhibit enhancement of viscosity in the Newtonian flow. Whereas Newtonian flow provides a precise definition of the long branches, it is not accessible for most of the elastomers. In the observed time scale, the linear viscoelastic properties as well as the steady-state viscosities are affected not only by branches but also by gels and molecular weight distribution. When these material variables are changed one at a time in the properly designed model systems, their effects are separately observable. On the other hand with a sample of unknown background, the effect of long branching is usually inseparable from those of other variables.

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