For unknown psychological reasons, the vast majority of viscoelastic measurements are presented as dynamic or stress relaxation modulus functions. To examine only modulus functions appears to be acceptable, because within a constant or two, all of the complete viscoelastic functions are mathematically equivalent. It is pointed out here, that most data are not practicably equivalent and that in numerous instances the compliance functions are more revealing concerning molecular orientational dynamics; especially those that are not influenced by viscous flow. The presence of shoulders or plateaus exhibited by the dynamic storage modulus G′ or the stress relaxation modulus G(t) functions, which can be mistaken for molecular entanglement plateaus, are shown to be present in some systems that contain no effective entanglements. The obfuscation caused by the viscous deformation in the terminal zone of behavior is emphasized. The additivity of different molecular mechanisms contributing to the compliance functions demand that decomposition be carried out on these functions, before further analysis is possible. Since the results from any dynamic measurement, which yields both storage and loss components of the modulus, can be algebraically transformed into the compliance components, investigators have nothing to lose but possibly much to gain by including the examination of the compliances as well as the moduli.
Skip Nav Destination
Article navigation
November 1992
Research Article|
November 01 1992
What’s wrong with the moduli Charley Brown? or Get the H out and go to L
Donald J. Plazek
Donald J. Plazek
Materials Science and Engineering Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
Search for other works by this author on:
J. Rheol. 36, 1671–1690 (1992)
Article history
Received:
January 12 1992
Accepted:
May 05 1992
Citation
Donald J. Plazek; What’s wrong with the moduli Charley Brown? or Get the H out and go to L. J. Rheol. 1 November 1992; 36 (8): 1671–1690. https://doi.org/10.1122/1.550279
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Citing articles via
Rheo-SINDy: Finding a constitutive model from rheological data for complex fluids using sparse identification for nonlinear dynamics
Takeshi Sato, Souta Miyamoto, et al.
Learning a family of rheological constitutive models using neural operators
Deepak Mangal, Milad Saadat, et al.
Linear viscoelasticity of nanocolloidal suspensions from probe rheology molecular simulations
Dinesh Sundaravadivelu Devarajan, Rajesh Khare
Related Content
Rheology of colloidal suspensions: Case of lubricating greases
J. Rheol. (July 1994)
Don’t cry for me Charlie Brown, or with compliance comes comprehension
J. Rheol. (July 2000)
Rheological analysis of highly pigmented inks: Flocculation at high temperatures
J. Rheol. (March 1998)
Melt viscosities and dynamic moduli for polyethylenes subjected to constant strain rate elongations with superimposed sinusoidal oscillations
J. Rheol. (July 1993)
Restrictions Upon Viscoelastic Relaxation Functions and Complex Moduli
Transactions of The Society of Rheology (December 1972)