Paper Number
RS1 

Session
Techniques and Methods: Rheometry & Spectroscopy/Microscopy

Title
Combined torsional-axial measurements in a single rheometer for determination of viscoelastic Poisson’s ratio

Presentation Date and Time
October 11, 2022 (Tuesday) 9:50

Track / Room
Track 6 / Mayfair

Authors (Click on name to view author profile)

  1. Rodríguez Agudo, José Alberto (Anton Paar Germany GmbH, Rheology)
  2. Haeberle, Jan (Anton Paar Germany GmbH, Rheology)
  3. Arnold, Gunther (Anton Paar Germany GmbH, Rheology)
  4. Shetty, Abhishek (Anton Paar USA Inc., Rheology Department, Advanced Technical Center)
  5. Giehl, Christopher (Anton Paar Germany GmbH, Rheology)

Author and Affiliation Lines (in printed abstract book)
José Alberto Rodríguez Agudo1, Jan Haeberle1, Gunther Arnold1, Abhishek Shetty2 and Christopher Giehl1
1Rheology, Anton Paar Germany GmbH, Ostfildern, Germany; 2Rheology Department, Advanced Technical Center, Anton Paar USA Inc., Ashland, VA 23005

Speaker / Presenter 
Shetty, Abhishek

Keywords
experimental methods; additive manufacturing; composite rheology; rheometry techniques

Text of Abstract
The lateral contraction of a material when stressing the material in axial direction is described by the Poisson’s ratio. In case of viscoelastic materials, like polymers, this parameter is a function temperature and excitation frequency in oscillatory mode, and important for e.g. structural mechanics simulations. Methods to describe to determine the viscoelastic Poisson’s ratio are manifold and can be classified in direct methods which directly measure the change of the specimen dimensions and indirect methods from which the measurement of two moduli like shear modulus and Young’s modulus seems to be the most effective. A new measuring device concept is introduced which combines an electronically commutated (EC) motor as rotational top drive and a moving magnet linear drive, as bottom drive to enable torsional and axial measurements on one single device. In this contribution measurements with both cylindrical and rectangular specimens are presented to determine the viscoelastic Poisson’s ratio of different solid polymers. Using a linear and a rotational measuring drive in one instrument enables the determination of complex Young’s modulus |E*| as well as the complex shear modulus |G*| on a single sample in a continuous measurement run. Consecutive frequency sweeps at room temperature in both, torsion and tension deformation modes were performed to obtain the viscoelastic Poisson’s ratio. A suite of polymers ranging from amorphous (PMMA, PC), thermoplastic polyurethane (TPU) to thermosets (Epoxy) were studied. For the case of amorphous polymers, a nonmonotonic increase of the complex Poisson’s ratio with temperature was found. For the rest of the polymers, a monotonic increase in the complex Poisson's ratio with temperature was observed, when approaching the glass transition temperature. The suitability of the method is further examined and discussed by comparing the experimental results on several polymers with literature data.