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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: Emerging Topics in Chemical and Polymer Physics, New Instruments and Methods II
CPP 15.2: Vortrag
Montag, 9. März 2026, 17:30–17:45, ZEU/0255
Chirp-DMA for expanded frequency and reduced aging — •Juan Pablo Segovia Gutiérrez1, José Alberto Rodríguez Agudo2, Jan Haeberle2, Dominic Oppen2, Jörg Läuger2, and Natalie Germann1 — 1University of Stuttgart, Stuttgart, Germany — 2Anton Paar Germany GmbH, Ostfildern, Germany
Optimal Fourier Rheometry (OFR), or Chirp rheometry, is an advanced technique that uses a continuous, sine wave-shaped stress/strain signal characterized by an exponential frequency increase. This approach is important for measuring rapidly time-evolving soft materials, where conventional frequency sweeps are impractical; their slow, sequential data acquisition often fails to capture fast structural changes before the material itself mutates. A key advantage of Chirp is its ability to drastically reduce measurement time, making it highly effective at low and very low frequencies. This speed is essential to circumvent undesirable material aging, for instance in the dehydration observed in hydrogels, which modifies properties during long acquisition times. Conventionally, Chirp has been implemented using standard plate-plate geometries. The novelty of this study is the implementation of Chirp within a Dynamic Mechanical Analysis (DMA) setup utilizing extension and torsion modes. This permits the characterization of soft, fragile materials outside the typical rheometer configuration. By combining this novel Chirp-DMA approach with conventional sweeps on gellan gum/alginate hydrogels, we extend the practical frequency range and prove that Chirp recovers true viscoelastic moduli, thereby eliminating dehydration-induced effects.
Keywords: Hydrogels; Chirp rheometry; Optimal Fourier Rheometry; Dynamic Mechanical Analysis; Frequency