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Small-Amplitude Oscillatory Shear Flow Measurements as a Tool To Detect Very Low Amounts of Long Chain Branching in Polyethylenes by J. F. Vega; A. Santamaría; A. Muñoz-Escalona; P. Lafuente is a Materials Science article available to read on EtoBox.

What is Small-Amplitude Oscillatory Shear Flow Measurements as a Tool To Detect Very Low Amounts of Long Chain Branching in Polyethylenes about?

Dynamic viscoelastic results of 23 noncommercial metallocene-catalyzed polyethylenes and poly(ethylene/1-hexene) copolymers, in the range 130-190 °C, are presented. The effects of welldetermined structural parameters such as molecular weight, polydispersity, and degree of short chain branching (SCB), are analyzed. The molecular weight varies between 60 000 and 325 000, the polydispersity between 1.8 and 7.3, and SCB between 0 and 48.5 branches/1000 C atoms. It is observed that a group of 11 polymers displays rheological specific features which can be summarized as follows: (a) higher dynamic viscosities at low frequencies than other polyethylenes and ethylene/1-hexene copolymers of similar molecular weight, polydispersity and SCB degree; (b) higher relaxation times than narrow molecular weight distribution polyethylenes of similar dynamic viscosities at low frequencies but similar relaxation times to those of broad molecular weight distribution; (c) higher values of elastic modulus, in comparison with polyethylenes of similar molecular weight, polydispersity, and SCB but of the same order of magnitude as those of broader molecular weight distribution; (d) higher activation energy o

Who reads Small-Amplitude Oscillatory Shear Flow Measurements as a Tool To Detect Very Low Amounts of Long Chain Branching in Polyethylenes?

Author

J. F. Vega; A. Santamaría; A. Muñoz-Escalona; P. Lafuente

Publisher

American Chemical Society (ACS)

Published

1998

Language

EN

Field

Materials Science (Physical Sciences)