BPI Seminar by Dr. Caterina Czibula

Micromechanics of Natural Fibers

LOCATION: PPC #210, Pulp & Paper Centre, 2385 East Mall, Vancouver, BC V6T 1Z4

Agenda

• 10:00 AM Intro by Dr. Mark Martinez
• 10:05 AM Presentation by Dr. Caterina Czibula, Postdoc, Materials Science and Engineering, Northwestern University
• 10:45 AM Q&A

Abstract

Classical material testing works well for engineering materials like metals, however, there are numerous complex material systems where conventional methods are limited. For soft, biological materials like tissue and cells it is difficult to determine the mechanical properties reliably. For technologically-relevant materials such as cellulose fibers which have a complex structure and anisotropic properties, it is nearly impossible to assess the mechanical response in all directions of the material with standard techniques. Furthermore, their natural variability leads to large scattering of the results, making contact measurements difficult to interpret.

In this talk, Brillouin Light Scattering Spectroscopy (BLS) is introduced as a non-contact, optical method to measure mechanical properties. BLS is based on the inelastic scattering of laser light by acoustic phonons. Thus, in contrast to Raman scattering, the light does not interact with local, molecular vibrational modes, but with collective density fluctuations in the material, enabling the measurement of a frequency shift that is directly linked to the elastic properties of the material via the speed of sound. As a consequence of the non-contact nature, BLS enables the measurement of the full elastic stiffness tensor without sample preparation by simply changing the scattering geometry.

Together, we will explore the elastic stiffness tensor of a cellulosic viscose fiber and I will emphasize the challenges connected with BLS. Furthermore, we will have a look at cellulose-water and cellulose-ionic liquid interactions and shine a light on their effects on the morphology as well as mechanical properties of single fibers. Especially the dissolution of cellulosic materials by ionic liquids is a very interesting approach and here, my colleague Lukas Pachernegg-Mair will take over for a few slides to tell you more about it. In the end, I will give you an outlook on my current work with keratin fibers such as wool and hair.

About the Speaker

Dr. Caterina Czibula studied Materials Science at the University of Mining in Leoben, Austria and received her Ph.D. there in 2020. From 2021-2024 she was holding a Hertha Firnberg Fellowship of the Austrian Science Fund. She participated in the Marcus Wallenberg Young researcher challenge in Stockholm 2023 and is recipient of the “For Women in Science Austria” Award, which is an initiative of L’Oréal and UNESCO. Currently, she is a postdoctoral researcher at Northwestern University in the SPIn (Sustainable Polymer Innovation) Lab of Ass. Prof. Cécile A. C. Chazot. Caterina considers herself a fiber girl and performs mechanical characterization on biopolymers from nano- to macro-scale, in the Hz to GHz regime by applying loads in the range of nN to kN.

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