Premium
Experimental investigation of the influence of molecular weight distribution on the rheological properties of polypropylene melts
Author(s) -
Minoshima Wataru,
White James L.,
Spruiell Joseph E.
Publication year - 1980
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760201710
Subject(s) - materials science , rheology , viscoelasticity , molar mass distribution , polypropylene , shear rate , elongation , viscosity , composite material , shear flow , newtonian fluid , thermodynamics , melt flow index , polymer , ultimate tensile strength , copolymer , physics
An experimental study of steady shear and elongational flow Theological properties of a series of polypropylene melts of varying molecular weight and distribution is reported. Broadening the molecular weight distribution increases the non‐Newtonian character of the shear viscosity function and increases the principal normal stress differences at fixed shear stress. The behavior is compared to earlier rheological property‐molecular weight studies. Correlations are developed for these properties in terms of molecular structure. Elongational flow studies indicate that for commercial and broader molecular weight distribution samples, ready failure by neck development occurs and the elongational viscosity appears to decrease with increasing elongation rate. For narrower molecular weight distribution samples, the elongational viscosity is an increasing function of elongation rate, The implication of these experimental results to viscoelastic fluid constitutive equations and polymer melt processing is developed.