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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 43: Biomaterials and Biopolymers (joint session BP/CPP)

CPP 43.6: Vortrag

Donnerstag, 12. März 2026, 10:45–11:00, BAR/SCHÖ

Power-Law Analysis of Force Relaxation and Creep Compliance in Nanoindentation of Glassy Gelatin in Humid Air — Paul Zech, Martin Dehnert, Mario Zerson, and •Robert Magerle — Fakultät für Naturwissenschaften, TU Chemnitz

Gelatin-based materials are widely used in food technology, drug delivery systems, and tissue engineering. Water acts as a plasticizer, softening gelatin and reducing its glass transition temperature. Using AFM-based nanoindentation experiments, we examined the mechanical response of a gelatin film to nanoindentations under constant strain (force relaxation) or constant stress (creep compliance) at a wide range of tip approach velocities and relative humidity levels. Scaling analysis using a fractional rheology model reveals that force relaxation and creep compliance exhibit universal power-law behavior. Temporal evolution depends only on the tip indentation time, which defines the externally imposed timescale of the process, and the power-law exponent α, which characterizes the degree of viscoelasticity. At relative humidity > 85%, the α values differ between the force relaxation and creep compliance data. This indicates differences in the underlying molecular processes.

Keywords: AFM nanoindentations; power-law rheology; glassy dynamics; gelatin; water