Dual-shape polymers cyclic, thermomechanical

Cyclic, Thermomechanical Tensile Tests of Dual-Shape Polymers. 118... 

Triple-shape polymers can change on demand from a first shape (A) to a second shape (B) and from there to a third shape (C), when stimulated by two subsequent temperature increases [10, 26, 27]. Specific cyclic, thermomechanical tensile experiments were developed to characterize the triple-shape effect (Chapter Shape-Memory Polymers and Shape-Changing Polymers [101] and Sect. 2.2) quantitatively. Analogous to the experiments for dual-shape materials, each cycle of these tests consisted of a programming and a recovery module. A cycle started with creating the two temporary shapes (B and A) by a two-step uniaxial deformation, followed by the recovery module, where shape (B) and finally shape (C) were recovered. 

The creation of the triple-shape capability for an AB polymer network system by a simple one-step process similar to a conventional dual-shape progranuning process was shown for networks based on PCL and PCHMA [24] (see Sect. 2.4). In these materials a stress-controlled cyclic, thermomechanical experiment was used to quantify the triple-shape effect. The sample was deformed at 150°C (liigh) to 50% (Ein) and subsequently cooled to —10°C (Tio ). The large temperature interval of around 160 K led to a strong reduction of the strain. When the sample was heated... 

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