ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Controlled-rheology polypropylene melts were prepared via molecular modification of a commercial polypropylene resin. A peroxide-initiated degradation was performed, resulting in materials with different molecular weight distributions. These resins were subjected to rheological characterization, and an integral constitutive equation of the K-BKZ type was used to study the effect of molecular weight characteristics on their rheological properties. Data for the linear viscoelastic spectrum and shear viscosities was used to obtain the model constants. The same constitutive equation has been used to predict the stress and Trouton ratios for simple shear and simple elongational flows, thus giving a quantitative assessment of the viscoelastic character of the melts. The results show the effect of the molecular modification on the rheological behavior of the melts. Polymers produced at higher peroxide concentrations exhibit reduced viscoelasticity manifested in less shear-and strain-thinning behavior. The present work clearly shows the potential of integral constitutive equations in fitting and interpreting experimental data and, thus, giving a much better understanding of the rheological behavior of commercial polymers. © 1996 John Wiley & Sons, Inc.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
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