Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Focus: Stress Relaxation in Polymers - From single molecules to biological cells (with CPP)

BP 21.3: Talk

Thursday, March 29, 2012, 10:15–10:30, C 243

Mechanical stress relaxation in polymers followed by low-field NMR — Ute Böhme and •Ulrich Scheler — Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, Germany

Low-field NMR provides information on molecular mobility over a wide range of rates of motion. In-situ low-field NMR has been applied on polymers under uniaxial stress [1]. Strongest stress-induced effects have been observed in T2 (indicative for slow motion) and T1rho (indicative for mtion of rates of kilohertz) both indicating restictions in the motion of polymer segments. In elastomers the changes a reversible after release of the external stress. Time-dependent experiments at constant extension on semicrystalline polymers show a return of both relaxation times to the values of the non-stressed sample. However, the time constant of that return is significantly longer than that observed in mechanical stress-relaxation experiments.

[1]Böhme, U.; Gelfert, K.; Scheler, U. Solid-state NMR of polymers under mechanical stress AIP conference proceedings 1330 (2011) 109