Stimuli-responsive hydrogels consist of a porous 3D framework that is saturated with solvent. Immersed in a solution bath, these gels can exhibit an enormous volume change due to absorption or release of solution. Depending on the type of gel, this effect can be generated for example by variation of the ion concentration in the surrounding solution bath or by an applied electrical field. The mechanical behavior of these polymers is influenced not only by the solid-state skeleton, but also by the interacting fluid. Thus, a visco-elastic behavior can be observed on the macroscopic scale. Based on the specific properties of the polymer gel and the interaction of the different phases, the determination of the mechanical properties of this material turns out to be non-trivial. In the present work, the mechanical behavior of a poly(acrylamide-co-sodium acrylate) hydrogel in the fully swollen state is investigated by a newly developed tensile test and for longtime investigations by a creep test. For this purpose, two newly developed different experimental setups based on digital image correlation are used.

刺激响应水凝胶由被溶剂饱和的多孔3D骨架组成。浸入溶液浴中的这些凝胶由于溶液的吸收或释放而可能显示出巨大的体积变化。取决于凝胶的类型，例如，可以通过改变周围溶液浴中的离子浓度或通过施加电场来产生这种效果。这些聚合物的机械性能不仅受固态骨架的影响，还受相互作用流体的影响。因此，可以在宏观尺度上观察到粘弹性行为。基于聚合物凝胶的特定性质和不同相的相互作用，确定这种材料的机械性质并非易事。在目前的工作中，通过新开发的拉伸试验研究了完全溶胀状态的聚丙烯酰胺-丙烯酸钠共聚物水凝胶的力学行为，并通过蠕变试验研究了长期的研究。为此，使用了两个基于数字图像相关性的新开发的不同实验设置。