Relationship between Annealing and Shape Memory Effect of Shape Memory Polyurethane

2014 ◽  
Vol 936 ◽  
pp. 140-144 ◽  
Author(s):  
Jia Ying ◽  
Masaaki Nishikawa ◽  
Masaki Hojo
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Length Change ◽  
Recovery Ratio ◽  
High Entropy ◽  
Change Of State ◽  
Relationship Of ◽  
Shape Memory Polyurethane

The relationship of annealing and shape memory effect of uniaxially oriented shape memory polyurethane was studied; meanwhile a new method of adjusting shape recovery ratio by annealing was proposed for further consideration. Experiments were designed to compare the influence on length change from annealing and shape memory effect with shape memory polyurethane film at 65°C. We found that for shape memory polyurethane which had residual strain from material processing procedure, annealing and shape memory effect have the same effect on its length change if they are both carried out at the same temperature. It is because annealing and shape memory effect have the same mechanism, which is the change of state from low conformational entropy states to the recovery of a stable high entropy state in the polymer. Moreover, it is proved by experiment that shape recovery ratio of shape memory polyurethane can be adjusted by annealing.

scholarly journals Thermally-Induced Shape-Memory Behavior of Degradable Gelatin-Based Networks

2021 ◽  
Vol 22 (11) ◽  
pp. 5892
Author(s):  
Axel T. Neffe ◽  
Candy Löwenberg ◽  
Konstanze K. Julich-Gruner ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Polymer Networks ◽  
Water Soluble ◽  
Compression Tests ◽  
Thermally Induced ◽  
Thermomechanical Process ◽  
Triple Helices

Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) α,ω-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27–23 kPa and Young’s moduli of 215–360 kPa at 4 °C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 °C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates Rr close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.

scholarly journals Microstructure Formation in Cast TiZrHfCoNiCu and CoNiCuAlGaIn High Entropy Shape Memory Alloys: A Comparison

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4227 ◽  
Author(s):  
Tetiana A. Kosorukova ◽  
Gregory Gerstein ◽  
Valerii V. Odnosum ◽  
Yuri N. Koval ◽  
Hans Jürgen Maier ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Microstructure Characterization ◽  
Microstructure Formation ◽  
High Entropy

The present study is dedicated to the microstructure characterization of the as-cast high entropy intermetallics that undergo a martensitic transformation, which is associated with the shape memory effect. It is shown that the TiZrHfCoNiCu system exhibits strong dendritic liquation, which leads to the formation of martensite crystals inside the dendrites. In contrast, in the CoNiCuAlGaIn system the dendritic liquation allows the martensite crystals to form only in interdendritic regions. This phenomenon together with the peculiarities of chemical inhomogeneities formed upon crystallization of this novel multicomponent shape memory alloys systems will be analyzed and discussed.

Effect of Tin Addition on Phase Constitution and Heat Treatment Behavior in Ti-40Ta-Sn Alloys

2004 ◽  
Vol 449-452 ◽  
pp. 1273-1276 ◽  
Author(s):  
Masahiko Ikeda ◽  
S. Komatsu ◽  
Yuichiro Nakamura ◽  
Y. Kobayashi
Keyword(s):  
Heat Treatment ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Resistivity Ratio ◽  
Phase Constitution ◽  
Recovery Test ◽  
Orthorhombic Martensite ◽  
Solution Treated

Using Ti-40mass%Ta-0, -4, -8 and -12mass%Sn alloys, the effect of Sn addition on phase constitution in the solution treated and quenched state and isochronal heat treatment behavior is studied by electrical resistivity and Vickers hardness measurements and X-ray diffactometry. To confirm shape memory effect of some of these alloys, shape-recovery test was also performed. Orthorhombic martensite, ” was identified in Ti-40Sn-0 to 8Sn alloy quenched from 1173K, while phase was identified in STQed Ti-40Ta-12Sn alloy. On isochronal heat treatment, increases of resistivity at LN and resistivity ratio were observed in only 8Sn alloy, because these increases are due to reverse-transformation of ” to phase. From result of shape recovery test, shape memory effect was observed in Ti-40Ta-4 and 8Sn alloys

Effect of Aging on Mechanical Properties of Ti-Mo-Al Biomedical Shape Memory Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2150-2153 ◽  
Author(s):  
Hideki Hosoda ◽  
Makoto Taniguchi ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Tensile Tests ◽  
Single Step ◽  
Two Phase ◽  
Solution Treated

Effects of single- and multi-step aging on mechanical properties and shape memory properties of Ti-6Mo-8Al (mol%) biomedical shape memory alloy were studied using tensile tests at room temperature (RT). The solution-treated alloy at RT was two phase of bcc β and martensite α". Tensile tests revealed that the solution-treated alloy exhibited good shape memory effect. As for the single-step aging, (1) pseudoelastic shape recovery by unloading was observed after aging at 623K, (2) the alloy became brittle after aging at 773K due to ω embrittlement, and (3) strength was improved with small shape memory effect by aging at 1023K. On the other hand, after a multistep aging at 773K-1023K-1123K, the alloy was strengthened and showed perfect shape recovery. The improvement must be achieved by the formation of fine and uniform hcp α precipitates.

Study on the Shape Memory Behavior of Poly (L-Lactide)

2005 ◽  
Vol 475-479 ◽  
pp. 2399-2402 ◽  
Author(s):  
Xili Lu ◽  
Wei Cai ◽  
Lian Cheng Zhao
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Amorphous Phase ◽  
Memory Effect ◽  
Crystalline Phase ◽  
Ring Opening ◽  
Shape Recovery ◽  
Ring Opening Polymerization ◽  
Bending Test ◽  
Shape Memory Behavior

Poly(L-lactide) (PLLA) was synthesized by the ring-opening polymerization of L-lactide and the shape memory behavior was studied using DSC and bending test experiments. The results indicate that the specimen shows the shape memory effect (SME), the small crystalline phase of PLLA and the mobility of amorphous phase may be responsible for the SME. The shape recovery of samples decreases and approaches to steady with the testing number increases.

scholarly journals Investigations of Effects of Intermetallic Compound on the Mechanical Properties and Shape Memory Effect of Ti–Au–Ta Biomaterials

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5810
Author(s):  
Wan-Ting Chiu ◽  
Kota Fuchiwaki ◽  
Akira Umise ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compound ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Population Aging ◽  
Chemical Compositions ◽  
Physical Metallurgy ◽  
World Population

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti–Au–Ta SMAs, which also possess high X–ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti–Au–Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta; in addition, obvious improvements of the alloy performances of the ternary Ti–Au–Ta alloys were confirmed while compared with that of the binary Ti–Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti–4 at.% Au–30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti–4 at.% Au–20 at.% Ta alloy during unloading of an externally applied stress.

The Effect of Some Factors on Ms and Sme in Ce-TZP Ceramics

1991 ◽  
Vol 246 ◽  
Author(s):  
Bohong Jiang ◽  
Jinbiao Tu ◽  
T.Y. Hsu ◽  
Zuyao Xu ◽  
Xuan Qi ◽  
...  
Keyword(s):  
Shape Memory ◽  
Intermetallic Compounds ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Recovery ◽  
Tetragonal Zirconia ◽  
Metallic Alloys ◽  
Maximum Deflection ◽  
Zirconia Ceramics ◽  
Shape Memory Behaviour

As known to all,shape memory behaviour has been observed in a variety of metallic alloys. This phenomenon, however, is not only observed in that field but also in other materials recently, such as in polymers,intermetallic compounds and ceramics, especially in zirconia ceramics.Swain [1] observed the shape recovery of a bent magnesia-partiallystabilized zirconia (Mg-PSZ) bar upon heating above a certain temperature. The maximum deflection which was nearly completely recovered on heating is about 300 μm.Chen et al [2] investigated the pseudoelasticity and shape memory effect (SME) in ceria-stabilized tetragonal zirconia polycrystals (Ce- TZP) containing 12 mol% CeO2.Wang et al [3] also observed the SME in Ce-TZP containing 10 mol% CeO2,.Here we would like to introduce some of results conducted recently in our group on SHE in Ce-TZP ceramics.

scholarly journals Investigation of shape memory effect in Ni-Ti based alloys

2021 ◽  
Vol 31 (4) ◽  
Author(s):  
Dan Nguyen Huy ◽  
Xuan Hau Kieu ◽  
Hai Yen Nguyen ◽  
Thi Thanh Pham ◽  
Huy Ngoc Nguyen ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Melt Spinning ◽  
High Strength ◽  
High Entropy ◽  
Practical Applications ◽  
Bone Anchors ◽  
Research Situation ◽  
Initial Results

Shape memory alloys (SMAs) are ones which can return to their original shape under impact of temperature or external magnetic field. The SMAs are capable of many applications in the fields of biomedical, aerospace, microelectronics, automation, for examples, orthodontics, stents, bone anchors, automatic valves, heat sensors, nanotweezers, robots... Recently, researchers have discovered the shape memory effect (SME) on high entropy alloys (HEAs). The combination of superior properties of SMAs and HEAs (high strength, heat resistance, low diffusion coefficient...) would bring useful practical applications in practice. In this paper, we will present an overview of the research situation of SMAs and our initial results obtained on Ni-Ti based alloys of Ni-Ti, Ni-Ti-Zr-Cu-Cr, Ni-Ti-Zr-Cu-Co, Ni-Ti-Zr-Cu-Nb, and Ni-Ti-Zr-Cu-Hf prepared by melt-spinning method.

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