Characterization of Creeping and Shape Memory Effect in Laser Sintered Thermoplastic Polyurethane

2016 ◽  
Vol 16 (4) ◽  
Author(s):  
Shangqin Yuan ◽  
Jiaming Bai ◽  
Chee Kai Chua ◽  
Kun Zhou ◽  
Jun Wei
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Thermal Transitions ◽  
Temperature Dependent ◽  
Shape Memory Effects ◽  
Viscoelastic Behaviors ◽  
High Flexibility

Thermoplastic polyurethane (TPU) powders were successfully processed in a selective laser sintering (SLS) system. The laser-sintered polyurethane products with viscoelastic behaviors exhibit high flexibility and elongation at break at room temperature. Moreover, the creeping and the thermoresponsive shape-memory effects (SME) were also characterized. The influences of the time-temperature relevant parameters on the shape-fixity and shape-recovery ratios were investigated quantitatively. The creeping and SME were time–temperature dependent phenomena, and the shape recovery mechanism is associated to the microsegments thermal transitions within the polymer matrix.

scholarly journals Hybrid Nanocomposites of Cellulose/Carbon-Nanotubes/Polyurethane with Rapidly Water Sensitive Shape Memory Effect and Strain Sensing Performance

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1586 ◽  
Author(s):  
Wu ◽  
Gu ◽  
Hou ◽  
Li ◽  
Ke ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Shape Memory ◽  
Shape Recovery ◽  
Thermoplastic Polyurethane ◽  
Cellulose Nanofibers ◽  
Hybrid Nanocomposites ◽  
Large Strains ◽  
Strain Sensing ◽  
Shape Memory Effects ◽  
Sensing Performance

In this work, a fast water-responsive shape memory hybrid polymer based on thermoplastic polyurethane (TPU) was prepared by crosslinking with hydroxyethyl cotton cellulose nanofibers (CNF-C) and multi-walled carbon nanotubes (CNTs). The effect of CNTs content on the electrical conductivity of TPU/CNF-C/CNTs nanocomposite was investigated for the feasibility of being a strain sensor. In order to know its durability, the mechanical and water-responsive shape memory effects were studied comprehensively. The results indicated good mechanical properties and sensing performance for the TPU matrix fully crosslinked with CNF-C and CNTs. The water-induced shape fixity ratio (Rf) and shape recovery ratio (Rr) were 49.65% and 76.64%, respectively, indicating that the deformed composite was able to recover its original shape under a stimulus. The TPU/CNF-C/CNTs samples under their fixed and recovered shapes were tested to investigate their sensing properties, such as periodicity, frequency, and repeatability of the sensor spline under different loadings. Results indicated that the hybrid composite can sense large strains accurately for more than 103 times and water-induced shape recovery can to some extent maintain the sensing accuracy after material fatigue. With such good properties, we envisage that this kind of composite may play a significant role in developing new generations of water-responsive sensors or actuators.

scholarly journals Shape-Memory-Recovery Characteristics of Microcellular Foamed Thermoplastic Polyurethane

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 351
Author(s):  
Chang-Seok Yun ◽  
Joo Seong Sohn ◽  
Sung Woon Cha
Keyword(s):  
Shape Memory ◽  
Cell Density ◽  
Shape Recovery ◽  
Structural Changes ◽  
Thermoplastic Polyurethane ◽  
Testing Machine ◽  
Base Material ◽  
Memory Mechanism ◽  
Foaming Process ◽  
Dog Bone

We investigated the shape-recovery characteristics of thermoplastic polyurethane (TPU) with a microcellular foaming process (MCP). Additionally, we investigated the correlation between changes in the microstructure and the shape-recovery characteristics of the polymers. TPU was selected as the base material, and the shape-recovery characteristics were confirmed using a universal testing machine, by manufacturing dog-bone-type injection-molded specimens. TPUs are reticular polymers with both soft and hard segments. In this study, we investigated the shape-memory mechanism of foamed polymers by maximizing the shape-memory properties of these polymers through a physical foaming process. Toward this end, TPU specimens were prepared by varying the gas pressure, foaming temperature, and type of foaming gas in the batch MCP. The effects of internal structural changes were investigated. These experimental variables affected the microstructure and shape-recovery characteristics of the foamed polymer. The generated cell density changed, which affected the shape-recovery characteristics. In general, a higher cell density corresponded to a higher shape-recovery ratio.

Shape memory effects of EVM-GMA/PVC blends

2020 ◽  
pp. 009524432095358
Author(s):  
Yanlu Chen ◽  
Zhengwei Lin ◽  
Haotian Zhao ◽  
Xingxing Ji ◽  
Xinyan Shi
Keyword(s):  
Shape Memory ◽  
Glycidyl Methacrylate ◽  
Shape Recovery ◽  
Physical And Mechanical Properties ◽  
Ethylene Vinyl Acetate ◽  
Recovery Efficiency ◽  
Restoring Force ◽  
Shape Memory Properties ◽  
Shape Memory Effects ◽  
Two Phases

In this paper, polyvinyl chloride (PVC) masterbatch, prepared using ethylene-vinyl acetate-glycidyl methacrylate terpolymer (EVM-GMA) as a polymer plasticizer replacing traditional harmful ester, was blended with EVM-GMA in melt and then cured by peroxide in a compression mold to prepare EVM-GMA/PVC blends. The results showed that with the increase of PVC, physical and mechanical properties have improved significantly. Two phases in blends formed a “sea-island” structure and the interface was blurred. Blends riched in EVM-GMA all had excellent dual shape memory properties. After removing applied force, there was only a slight recovery of the instantaneous elastic deformation and blends still retained the original temporary shape (the shape fixation was more than 99%). The shape recovery efficiency of specimen (EVM-GMA/PVC = 90/10) was the highest, which evidenced that entropy elastic effect of molecular chains and elastic restoring force provided by crosslinked structure achieved a balance at this point.

Shape Recovery and ε - γ Transformation in Fe29Mn7Si5Cr SMA

2008 ◽  
Vol 59 ◽  
pp. 86-91 ◽  
Author(s):  
Nele Van Caenegem ◽  
Kim Verbeken ◽  
Roumen H. Petrov ◽  
N.M. van der Pers ◽  
Yvan Houbaert
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Recovery ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Shape Memory Behaviour ◽  
Backscatter Diffraction

The shape memory behaviour of a Fe29Mn7Si5Cr based alloy has been investigated. Characterization of the martensitic transformation and the different structural constituents was performed using optical microscopy, X-ray diffraction (XRD) methods and electron backscatter diffraction (EBSD). The transformation temperatures and the shape recovery were determined by dilatometry on prestrained samples.

Classification and Characterization of the Shape Memory Binary Alloys

2006 ◽  
Vol 980 ◽  
Author(s):  
Mitsuo Notomi ◽  
Krystyn J Van Vliet ◽  
Sidney Yip
Keyword(s):  
Crystal Structure ◽  
Shape Memory ◽  
Shape Recovery ◽  
Major Element ◽  
Binary Alloys ◽  
Major Elements ◽  
The Other ◽  
Atomic Composition ◽  
Group 5

AbstractAll shape memory binary alloys (SMBA) that exhibit not only perfect shape recovery but also partial shape recovery were reviewed and classified into three groups, B2, A2 and A1 type, according to the parent phases. There are the thirteen, six and eleven alloys belonging to B2, A2 and A1 type, respectively. In the group of B2 type SMBA the alloys are divided into two categories due to the combination of the elements. Over A1 and A2 type SMBA the atomic composition of one element is larger than the other so the larger one is called a major element. The major elements, Ti, U, Fe, and Cu, of A2 type SMBA do not belong to the group 5 and 6 in which the elements have a typical BCC (A2) crystal structure. In the A1 type SMBA there are four major elements, Mn, Fe, Co, and In and the SMBA except for In-based SMBA have ferromagnetic or antiferromagnetic natures. The shape memory effect (SME) for A1 (FCC) type SMBA might need the magnetic properties.

Solvent-driven temperature memory and multiple shape memory effects

Soft Matter ◽  
2015 ◽  
Vol 11 (20) ◽  
pp. 3977-3985 ◽  
Author(s):  
Rui Xiao ◽  
Jingkai Guo ◽  
David L. Safranski ◽  
Thao D. Nguyen
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Memory Effects ◽  
Shape Memory Effects

Programmed Nafion specimens can achieve multi-staged shape recovery in multiple solvents.

High-throughput characterization of shape memory thin films using automated temperature-dependent resistance measurements

2005 ◽  
Vol 894 ◽  
Author(s):  
Sigurd Thienhaus ◽  
Christiane Zamponi ◽  
Holger Rumpf ◽  
Jae Hattrick-Simpers ◽  
Ichiro Takeuchi ◽  
...  
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Throughput ◽  
Thermal Hysteresis ◽  
Wafer Level ◽  
Magnetic Shape Memory ◽  
Temperature Dependent ◽  
Characterization Of Materials

AbstractShape memory alloy (SMA) thin films are used as actuator materials in MEMS due to their unique properties. Binary thin films with a composition close to Ni50Ti50 are well-established materials, whereas ternaries like NiTiCu, NiTiPd, NiTiHf are less studied. Furthermore, new alloys are being developed which show a magnetic shape memory effect, e.g. Ni2MnGa. For the optimization of known, and the development of new, SMA thin films, a fast and reliable characterization technology is needed, which rapidly identifies the transformation temperatures (i.e. martensite and austenite start and finish temperatures) for a range of material compositions deposited on a whole wafer. In this paper, automated temperature-dependent resistance measurements are discussed as a means which yields the thermal hysteresis of the investigated thin films. Results of monitoring the uniformity of shape memory film depositions on the wafer level, as well as results on the use of this method as a tool for screening for new SMA films by characterization of materials libraries are reported.

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