Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Poster: Stress Relaxation in Polymers - From single molecules to biological cells (joint focus with BP)
CPP 25.11: Poster
Mittwoch, 28. März 2012, 11:00–13:00, Poster A
The effect of moisture on mechanical deformation of PETG — •masoud amirkhani1, Andrew Boryor2, Juliana Kurniadi3, Martin Geiger2, Thanapon Panchapongsaphak2, Othmar Marti1, and Bernd Lapatki2 — 1Institute of Experimental Physics, University of Ulm, Germany — 2Department of Orthodontics, University of Ulm, Germany — 3DWI at RWTH Aachen e.V. and ITMC / TexMC, RWTH Aachen University, Germany
In this work, we studied the deformation properties of polymer systems in the presence of the water molecules. Depending on the type of polymer network, water molecule may cause softening or hardening of the network. This study shows that polyethylene terephthalate (PETG) immersed in water initially swells whereby its stiffness decreases but after a certain time its stiffness increased to almost its initial point as shown in Figure 1. We applied three-point bending experiments on several stripes (10mm x 55mm) of PETG immersed in water for 14 days. The experiments showed that the elastic modulus of the tested PETG material decreases until 30 hours, after which a gradual increase in the elastic modulus was experienced until 14 days where the E-module almost reached that of the dry material. The reduction of the elastic modules is due to plasticiser effect, which is caused by dispersing water molecules in the network. The increase in stiffness after 30 hours can be attributed to the rearrangement of the polymer chain which also causes a repelling of the water molecules from the polymer network.