抄録
It is the object of the present study to obtain clear knowledge of the relations in the polypropylene melt between its linear viscoelasticity and its non-linear steady capillary flow, paying particular attention to the elastic properties in its capillary flow
By representing the linear viscoelasticity numerically with zero-shear viscosity, ηo, and steady-state compliance, Je0, evaluation has been made of the properties concerning the elasticity of polymer in the capillary flow, such as non-Newtonianity, the entrance pressure loss, the end correction, the Barus effect and the melt fracture.
The steady flow viscosity, η, the entrance pressure loss, Po, the critical shear stress, τc, and the critical shear rate, γc, at which melt fracture begins to occur, are subject to ηo as follows:
logη∝logηo, logPo∝logηo, τc∝-logηo, logγc∝-logηo.
From the well-known relationship between ηo and the average molecular weight, Mw, these quantities are governed by Mw.
Meanwhile, for such quantities as structural viscosity index, N, end correction coefficient, ν, and elastic pressure loss ratio, Po/P, following correlations hold: N∝log(ηo, Je0), logν∝log (ηo2·Je0), Po/P∝log(ηo2·Je0).
As ηo and Je0 are respectively determined mainly by Mw and the molecular weight distribution, M.W.D., these quantities are governed by both Mw and M.W.D.
Physical meanings of ηo·Je0 and ηo2·Je0 are respectively mean relaxation time and a measure of stored energy in steady flow. Barus effect has positive correlation to Je0, ν and Po/P
The symbol employed here, ∝, means the positive correlation.
