scholarly journals Nanoclay Modification of Shape Memory Polyurethane

2015 ◽  
Vol 15 (4) ◽  
pp. 327
Author(s):  
J. Dyana Merline ◽  
Reghunadhan Nair, C.P.
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Clay Content ◽  
Bending Test ◽  
Modulus Ratio ◽  
Tem Analysis ◽  
Shape Memory Property ◽  
Nanoclay Content ◽  
Shape Memory Polyurethane ◽  
Memory Characteristics

Effect of nanoclay modification on the properties of  polytetramethylene oxide-based polyurethane was examined. Nanoclay was dispersed in polyurethane wherein the clay content was varied from 1 to 5 wt.%. The nanocomposites were characterized by thermal, FTIR, XRD and thermo-mechanical analyses and their shape memory properties were evaluated. Morphology was examined by TEM analysis. Bending test<br />was adopted for the evaluation of shape memory property. Increase in clay content resulted an increase in transition temperature. Tensile strength and modulus increased proportional to nanoclay content. The elongation decreased with clay content. Intercalated structure of clay in the PU matrix was observed<br />from XRD studies, which was confirmed by TEM analysis. Modulus ratio showed a decreasing trend with nanoclay content. This resulted in decreased shape recovery characteristics. Highest shape recovery of 92% was observed for PU with 1 wt.% clay content. Moderate nanoclay leveling is conducive to deriving<br />mechanically stronger PU without loss of shape memory characteristics.

scholarly journals Carbon / Epoxy Resin Based Elastic Memory Composites

2012 ◽  
Vol 14 (3) ◽  
pp. 227 ◽  
Author(s):  
J. Dyana Merline ◽  
C.P. Reghunadhan Nair
Keyword(s):  
Glass Transition ◽  
Flexural Strength ◽  
Shape Memory ◽  
Shape Recovery ◽  
Diglycidyl Ether ◽  
Bending Test ◽  
Different Types ◽  
Elastic Memory Composites ◽  
Memory Characteristics ◽  
Epoxy Systems

Elastic memory composites were processed from shape memory epoxy resins and carbon fabric reinforcements. Three different types of epoxies (diglycidyl ether of bisphenol-A, tris(4-glycidyloxy phenyl)methane, and epoxy novolac) were used as matrices. Developed composites were evaluated for flexural strength and analyzed by Dynamic Mechanical Thermal analysis. Of the three different epoxy systems with carbon: resin ratio of 50:50, the composite with diepoxy system exhibited maximum glass transition value of 119 °C, epoxy novalac system exhibited a low glass transition value of 54 °C and the tris epoxy system exhibited a glass transition of 100 °C respectively. The flexural strength and modulus of the composites were optimised at a concentration of 40 wt.%. The transition temperature also showed a maximum at around this composition. Bending test was adopted for the shape memory evaluation. All the developed composites exhibited more than 90% shape recovery. The diepoxy resin series of composites exhibited the maximum shape recovery of 97%. The shape recovery properties of the tris epoxy and epoxy novolac-based composites were inferior. For the diepoxy resin-based system, the shape recovery time was proportional to the resin content. The shape recovery of composite with 80% resin was demonstrated experimentally. The properties of the composites show that these systems have the required elastic memory characteristics for possible use in thermo-responsive self-deployable applications.

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.

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 Study of Shape Memory and Tensile Property of 3D Printed Sinusoidal Sample/Nylon Composite Focused on Various Thicknesses and Shape Memory Cycles

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1600 ◽  
Author(s):  
Shahbaj Kabir ◽  
Sunhee Lee
Keyword(s):  
Shape Memory ◽  
Tensile Property ◽  
Shape Recovery ◽  
Cycle Number ◽  
Shape Memory Property ◽  
Memory Property ◽  
Fused Deposition ◽  
Initial Modulus ◽  
3D Printed ◽  
Nylon Composite

This study evaluated the shape memory and tensile property of 3D-printed sinusoidal sample/nylon composite for various thickness and cycles. Sinusoidal pattern of five thicknesses: 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm were 3D-printed on nylon fabric by the fused deposition modeling (FDM) 3D printer using shape memory thermoplastic polyurethane (SMTPU). Afterward, shape memory and tensile property was investigated up to 50 shape memory cycles. The study found that 3D-printed sinusoidal sample/nylon composite had a 100% shape recovery ratio for various thicknesses up to 50 cycles. The average shape recovery rate gradually decreased from 3.0°/s to 0.7°/s whereas the response time gradually increased with the increase of a 3D-printed pattern thickness. The stress and initial modulus gradually increased with the increase of the cycle’s number. Thus, the shape memory property had a similar tendency for various cycles whereas the tensile property gradually increased with the increase of the cycle number. Moreover, this study demonstrated that this 3D-printed sinusoidal sample/nylon composite can go through more than 50 cycles without losing its tensile or shape memory property. This 3D-printed sinusoidal sample/nylon composite has vast potential as smart, reinforced, and protective clothing that requires complex three-dimensional shapes.

scholarly journals Shape Memory Polyurethane Biocomposites Based on Toughened Polycaprolactone Promoted by Nano-Chitosan

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 225 ◽  
Author(s):  
Arvind Gupta ◽  
Beom Soo Kim
Keyword(s):  
Shape Memory ◽  
Biomedical Applications ◽  
Shape Recovery ◽  
Permanent Deformation ◽  
Testing Machine ◽  
Microscopic Analysis ◽  
Original Form ◽  
Electron Microscopic ◽  
Unique Shape ◽  
Shape Memory Polyurethane

The distinctive ability to remember their original form after partial or complete deformation makes shape memory polymers remarkable materials for several engineering and biomedical applications. In the present work, the development of a polycaprolactone based toughened shape memory polyurethane biocomposite promoted by in situ incorporation of chitosan flakes has been demonstrated. The chitosan flakes were homogeneously present in the polymer matrix in the form of nanoflakes, as confirmed by the electron microscopic analysis and probably developed a crosslinked node that promoted toughness (a > 500% elongation at break) and led to a ~130% increment in ultimate tensile strength, as analyzed using a universal testing machine. During a tensile pull, X-ray analysis revealed the development of crystallites, which resulted from a stress induced crystallization process that may retain the shape and melting of the crystallites stimulating shape recovery (with a ~100% shape recovery ratio), even after permanent deformation. The biodegradable polyurethane biocomposite also demonstrates relatively high thermal stability (Tmax at ~360 °C). The prepared material possesses a unique shape memory behavior, even after permanent deformation up to a > 500% strain, which may have great potential in several biomedical applications.

Grafting of shape memory polyurethane with poly(ethyleneimine) and the effect on electrolytic attraction in aqueous solution and shape recovery properties

2011 ◽  
Vol 20 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Yong-Chan Chung ◽  
Jong Shin Park ◽  
Chang Hoon Shin ◽  
Jae Won Choi ◽  
Byoung Chul Chun
Keyword(s):  
Aqueous Solution ◽  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polyurethane

Deformation of Biomedical AuCuAl-Based Shape Memory Alloy Micropillars

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1411-1415 ◽  
Author(s):  
Akira Umise ◽  
Rui Serizawa ◽  
Sari Yanagida ◽  
Kenji Goto ◽  
Masaki Tahara ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Recovery ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Transformation Strain ◽  
Xrd Analysis ◽  
Second Phase ◽  
Shape Memory Property ◽  
Good Shape

ABSTRACTThe deformation behavior and shape recovery of an Fe-added AuCuAl shape memory alloy micropillar were investigated. XRD analysis revealed that Au-28Cu-22Al-2Fe (at.%) alloy contained a second phase which was evaluated to be α-Fe (bcc). SEM observation also confirmed the second phase at the surface of the micropillar specimen. A polycrystalline micropillar with 20 x 20 x 40μm rectangular was fabricated by a focused ion beam (FIB) system, and micro compress test was performed at room temperature. It was found that the yield stress of micropillar showed 50MPa, which must correspond to stress for inducing martensite. After the heating of the compressed micropillar, 1.75% shape recovery was recognized which is comparable to the transformation strain. Then, the Fe-added AuCuAl micropillar was concluded to possess good shape memory property, and thus this alloy may be suitable for small endovascular treatment which requires good X-ray radiography.

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