Probing Submillimeter Dynamics to Access
Static Shear Elasticity from Polymer Melts
to Molecular Fluids
9
Laurence Noirez
Contents
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Empirical Origins of the Viscoelastic Approach in Polymer Dynamics and Limitations . . . . . 252
Hidden Experimental Difficulties Inherent to a Viscoelastic Measurement and to the
Determination of a Viscoelastic Time . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Optimizing the Stress Transmission in Viscoelastic Measurements and Scanning
the Submillimeter Scale Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
From Surface-Induced Solidification to the Identification of the Submillimeter
Shear Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
Generalization of the Submillimeter Shear Elasticity to Fluids and Liquids . . . . . . . . . . . . . . . . . . 261
Shear Elasticity and Surface Tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Relationships Between Low-Frequency Shear Elasticity and Conventional Viscoelasticity . . . 263
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
Abstract
At the millimeter scale and above, liquids and viscoelastic liquids are characterized by an absence of shear elasticity at low frequency (~Hz) in contrast to solids
or plastic fluids that need to exceed a stress threshold to flow. Below the
millimeter scale, the dynamic response exhibits viscoelastic moduli much higher
than those measured at larger scale and reveals that fluids possess finite shear
elasticity at low frequency. The low-frequency shear elasticity is identified on
unentangled and entangled polymers away from the glass transition, molecular
glass formers, alkanes, and H-bond liquids, from several tenths to hundredths of
L. Noirez (*)
Laboratoire Léon Brillouin (CEA-CNRS), Université Paris-Saclay, CEA-Saclay, Gif-sur-Yvette
Cédex, France
e-mail: laurence.noirez@cea.fr
© Springer Nature Switzerland AG 2020
L. Zhu, C. Y. Li (eds.), Liquid Crystalline Polymers, Polymers and Polymeric
Composites: A Reference Series, https://doi.org/10.1007/978-3-030-43350-5_54
249
Static Shear Elasticity from Polymer Melts
to Molecular Fluids
9
Laurence Noirez
Contents
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Empirical Origins of the Viscoelastic Approach in Polymer Dynamics and Limitations . . . . . 252
Hidden Experimental Difficulties Inherent to a Viscoelastic Measurement and to the
Determination of a Viscoelastic Time . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Optimizing the Stress Transmission in Viscoelastic Measurements and Scanning
the Submillimeter Scale Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
From Surface-Induced Solidification to the Identification of the Submillimeter
Shear Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
Generalization of the Submillimeter Shear Elasticity to Fluids and Liquids . . . . . . . . . . . . . . . . . . 261
Shear Elasticity and Surface Tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Relationships Between Low-Frequency Shear Elasticity and Conventional Viscoelasticity . . . 263
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
Abstract
At the millimeter scale and above, liquids and viscoelastic liquids are characterized by an absence of shear elasticity at low frequency (~Hz) in contrast to solids
or plastic fluids that need to exceed a stress threshold to flow. Below the
millimeter scale, the dynamic response exhibits viscoelastic moduli much higher
than those measured at larger scale and reveals that fluids possess finite shear
elasticity at low frequency. The low-frequency shear elasticity is identified on
unentangled and entangled polymers away from the glass transition, molecular
glass formers, alkanes, and H-bond liquids, from several tenths to hundredths of
L. Noirez (*)
Laboratoire Léon Brillouin (CEA-CNRS), Université Paris-Saclay, CEA-Saclay, Gif-sur-Yvette
Cédex, France
e-mail: laurence.noirez@cea.fr
© Springer Nature Switzerland AG 2020
L. Zhu, C. Y. Li (eds.), Liquid Crystalline Polymers, Polymers and Polymeric
Composites: A Reference Series, https://doi.org/10.1007/978-3-030-43350-5_54
249