Online Seminar series „Würzburger Tage“

DMA, Dielectrics and more - What can you learn about your polymer material with a rheometer besides moduli and viscosities?

Thursday, October 28th, 2021
10:00 am – 11:30 am CEST

The event is held via TEAMS. Participation is free of charge.

Rheology on polymers - More than just mechanical information
10:00 – 11:00 CEST

Rheology is the science of flow and deformation behavior and allows the determination of numerous mechanical properties of polymer materials such as viscosity, moduli and glass transition temperatures. By using advanced accessories, it is also possible to obtain additional information beyond this. For example, combinations with optical methods such as microscopy or light scattering allow deeper “insights” into the sample, and spectroscopy provides further helpful chemical information during rheological measurements. The influence of external electromagnetic fields on rheology is also an important factor in the assessment of new materials.

Development of Rheo-IR: combination of a strain-controlled rheometer and FTIR for mechano-chemical analysis of complex materials
11:00-11:30 CEST

Fourier-transform infrared (FTIR) spectroscopy is a common tool for determining the chemical composition of a material in the solid, liquid, or gas phase, both qualitatively and quantitatively. It is also used to follow the rate at which chemical changes occur. Polymerization kinetics, rubber crosslinking, and epoxy curing, to name a few, are examples of chemical changes that can have rheological implications. We present the design of an IR transparent upper-plate rheological geometry that can be used to sample attenuated total reflectance (ATR). We also describe the technical and methodological modifications made to the ATR crystal and two off-axis parabolic mirrors in order to combine FTIR and rheological measurements in an ARES G2. This allows for the acquisition of online and directly correlated real-time FTIR spectra while conducting rheological measurements. This makes it possible to correlate macroscopic rheological properties with microscopic and molecular chemical changes in real time.

This newly developed method was used in a dilute water-based solution to correlate the polymer network formation for a free-radical copolymerization of acrylic acid and methylenebis(acrylamide) as a crosslinking agent via IR spectroscopy and the respective mechanical time evolution. It has further been used to monitor the hydration kinetics as a function of structural build-up for cement paste.

Topics discussed will be:

  • Why coupling rheometers with other techniques is useful
  • Rheo-Optics – “Insights” into the sample during rheological measurements
  • Influence of external fields on mechanical properties: magneto- and electrorheology
  • Extending the frequency range: Rheo-dielectrics
  • Development of custom combinations: Rheo-IR for in-situ mechanical and chemical analysis of complex materials


About The Speakers

Dr. Lukas Schwab is the application specialist for mechanical testing at TA Instruments in Germany. He is the contact person for all questions concerning the use of rheometers, DMA and rubber testing instruments and helps users to make optimal use of their measuring instruments. After studying chemistry at KIT in Karlsruhe with a focus on polymer chemistry, he completed his doctorate there in the research group of Prof. Manfred Wilhelm on the topic of nonlinear rheology of rubbers before joining TA Instruments in 2016.

Nonkululeko Radebe is a scientific researcher at the Karlsruhe Institute of Technology (KIT), Germany, and is completing a PhD in Physical Chemistry. Her project is focused on the development and optimization of combined rheological and spectroscopic techniques in order to simultaneously study the physical and chemical properties of cementitious materials. She is a member the Sub-Saharan Africa representative on the RILEM Youth Council (RYC) which aims to attract, engage with and facilitate networking between young researchers and more experienced researchers. Apart from being a researcher, she is also passionate about education and involving young children in science through mediums of art, which she does through her organization, ArtScie, a development program based in South Africa.

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* Some modules and OEM products are excluded. Trade in required to receive discount. Please contact your local TA representative for more details. Deals valid for systems purchased and delivered before September 18, 2020.