Paper Number
ET31 

Session
Advanced Experimental Techniques/Methods in Rheology

Title
Probing the rheological properties of natural and synthetic fibers with a simple torsional pendulum

Presentation Date and Time
October 18, 2018 (Thursday) 10:50

Track / Room
Track 5 / San Felipe Room

Authors (Click on name to view author profile)

  1. Keshavarz, Bavand (Massachusetts Institute of Technology, Mechanical Engineering)
  2. Zarket, Brady (L'Oréal, Advanced Research)
  3. McKinley, Gareth H. (Massachusetts Institute of Technology)
  4. Holten-Andersen, Niels (Massachusetts Institute of Technology, Materials Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Bavand Keshavarz1, Brady Zarket2, Gareth H. McKinley3, and Niels Holten-Andersen1
1Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; 2Advanced Research, L'Oréal, Clark, NJ 07066; 3Massachusetts Institute of Technology, Cambridge, MA 02139

Speaker / Presenter 
Keshavarz, Bavand

Text of Abstract
Understanding the mechanical properties of natural and synthetic fibers is of great importance in many biological and industrial applications. Microscopic techniques such as micro/nano indentation already exist but these tests are often hard to perform and there are certain limitations in macroscopic interpretations of the obtained results. We explore the properties of a series of natural and synthetic fibers, with a simple torsional pendulum. The torsional oscillation of the mass-fiber system is precisely recorded with an HD video-camera and an image processing algorithm is used to analyze the resulting videos. Analysis of the processed images show a clear damped oscillatory response and a simple mechanical model can describe the amplitude decay of the oscillation data very well. The natural frequency of the oscillation and the corresponding damping ratio can be extracted using a logarithmic decrement method and directly connected to the bulk viscoelastic properties of the fiber plus any surface coating or ‘sizing’ that might be applied. We further study the sensitivity of these measurements to the chemo-mechanical properties of the outer layers of the fiber structure at different levels of humidity and pH. A parallel series of tests are performed on a strain-controlled rheometer in both torsional and elongational deformation modes. Results from this study can help us understand the effects of chemistry and microstructure on mediating the final mechanical properties of natural/industrial fibers.