Characterization of shape recovery via creeping and shape memory effect in ether-vinyl acetate copolymer (EVA)

2013 ◽  
Vol 20 (8) ◽  
Author(s):  
X. L. Wu ◽  
W. M. Huang ◽  
H. X. Tan
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Shape Recovery ◽  
Acetate Copolymer

scholarly journals Design of Ethylene-Vinyl Acetate Copolymer Fiber with Two-Way Shape Memory Effect

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1599 ◽  
Author(s):  
Xiaoming Qi ◽  
Wentong Yang ◽  
Laiming Yu ◽  
Wenjun Wang ◽  
Haohao Lu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Crosslink Density ◽  
Melt Spinning ◽  
Uv Curing ◽  
Ethylene Vinyl Acetate ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties, and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC, and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 261.86 ± 13.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators, and artificial muscles.

scholarly journals Design of ethylene-vinyl acetate copolymer fiber with two-way shape memory effect

2019 ◽  
Author(s):  
Xiaoming Qi ◽  
Wentong Yang ◽  
Laiming Yu ◽  
Wenjun Wang ◽  
Haohao Lu ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Vinyl Acetate ◽  
Memory Effect ◽  
Crosslink Density ◽  
Melt Spinning ◽  
Uv Curing ◽  
Ethylene Vinyl Acetate ◽  
Acetate Copolymer ◽  
Ethylene Vinyl Acetate Copolymer

One-dimensional shape memory polymer fibers (SMPFs) have obvious advantages in mechanical properties, dispersion properties and weavability. In this work, a method for fabricating semi-crystallization ethylene-vinyl acetate copolymer (EVA) fiber with two-way shape memory effect by melt spinning and ultraviolet (UV) curing was developed. Here, the effect of crosslink density on its performance was systematically analyzed by gel fraction measurement, tensile tests, DSC and TMA analysis. The results showed that the crosslink density and shape memory properties of EVA fiber could be facilely adjusted by controlling UV curing time. The resulting EVA fiber with cylindrical structure had a diameter of 247.13 ± 10.07 μm, and its mechanical strength and elongation at break were 64.46 MPa and 114.33%, respectively. The critical impact of the crosslink density and applied constant stress on the two-way shape memory effect were analyzed. Moreover, the single EVA fiber could lift more than 143 times its own weight and achieve 9% reversible actuation strain. The reversible actuation capability was significantly enhanced by a simple winding design of the single EVA fiber, which provided great potential applications in smart textiles, flexible actuators and artificial muscles.

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.

Synthesis and characterization of biodegradable, amorphous, soft IPNs with shape-memory effect

2011 ◽  
Vol 23 (3) ◽  
pp. 382-388 ◽  
Author(s):  
Yakai Feng ◽  
Haiyang Zhao ◽  
Licai Jiao ◽  
Jian Lu ◽  
Heyun Wang ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Synthesis And Characterization

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 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.

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