scholarly journals The Influence of Water and Solvent Uptake on Functional Properties of Shape-Memory Polymers

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Ehsan Ghobadi ◽  
Axel Marquardt ◽  
Elias Mahmoudinezhad Zirdehi ◽  
Klaus Neuking ◽  
Fathollah Varnik ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Holding Time ◽  
Fickian Diffusion ◽  
Recovery Ratio ◽  
Solvent Uptake ◽  
Time Shape ◽  
Influence Of Water ◽  
Shape Fixity

In this contribution, diffusion of water, acetone, and ethanol into a polymer matrix has been studied experimentally and numerically by finite element approaches. Moreover, the present study reports an assessment of different thermomechanical conditions of the shape-memory (SM) performance, for example, stress- or strain-holding times in stress- or strain-controlled thermomechanical cycles and the effect of maximum strain. According to the results presented here, the uptake of acetone in Estane is much higher than ethanol and follows classical Fickian diffusion. Further, a series of thermomechanical measurements conducted on dry and physically (hydrolytically) aged polyether urethanes revealed that incorporation of water seems to have an appreciable impact on the shape recovery ratios which can be attributed to the additional physical crosslinks. However, no obvious difference in shape fixation of dry and physically (hydrolytically) aged samples could be recognized. Furthermore, by decreasing the strain-holding time, shape recovery improves significantly. Moreover, the shape fixity is found to be independent of holding time. The shape recovery ratio decreased dramatically with an increase in the stress-holding time.

High-Strain Shape-Memory Properties of Poly(Carbonate-Urea-Urethane)s Based on Aliphatic Oligocarbonates and L-Lysine Diisocyanate

MRS Advances ◽  
2017 ◽  
Vol 2 (47) ◽  
pp. 2529-2536
Author(s):  
Magdalena Mazurek-Budzyńska ◽  
Muhammad Y. Razzaq ◽  
Gabriel Rokicki ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Medical Devices ◽  
Shape Recovery ◽  
High Strain ◽  
Shape Memory Polymers ◽  
Interesting Candidate ◽  
Degradable Biomaterials ◽  
Precursor Route ◽  
Shape Fixity ◽  
Poly Carbonate

ABSTRACTThe simultaneous capability of high-strain deformation and high shape recovery ratio constitutes a great challenge in design of the shape-memory polymers. Here we report on poly(carbonate-urea-urethane)s (PCUUs) synthesized by a precursor route, based on oligo(alkylene carbonate) diols, L-lysine diisocyanate (LDI), and water vapor. When programed with a strain of εprog = 800%, the PCUU networks exhibited a one-way shape-memory effect (1W-SME) with excellent shape fixity (> 97%) and shape recovery (> 99%) ratios. The switching temperatures (Tsw) varied between 50 and 56 °C and correlated to the melting transitions of the switching domains. The obtained PCUUs capable of high-strain are interesting candidate materials for degradable biomaterials as required in smart medical devices.

scholarly journals Effect of PEW and CS on the Thermal, Mechanical, and Shape Memory Properties of UHMWPE

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 483
Author(s):  
Run Zhang ◽  
Suwei Wang ◽  
Jing Tian ◽  
Ke Chen ◽  
Ping Xue ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Effect Of Temperature ◽  
Comprehensive Performance ◽  
Shape Memory Properties ◽  
Polyethylene Wax ◽  
Entanglement Network ◽  
Ultra High Molecular Weight ◽  
Shape Fixity

Modified ultra-high-molecular-weight polyethylene (UHMWPE) with calcium stearate (CS) and polyethylene wax (PEW) is a feasible method to improve the fluidity of materials because of the tense entanglement network formed by the extremely long molecular chains of UHMWPE, and a modified UHMWPE sheet was fabricated by compression molding technology. A Fourier-transform infrared spectroscopy test found that a new chemical bond was generated at 1097 cm−1 in the materials. Besides, further tests on the thermal, thermomechanical, mechanical, and shape memory properties of the samples were also conducted, which indicates that all properties are affected by the dimension and distribution of crystal regions. Moreover, the experimental results indicate that the addition of PEW and CS can effectively improve the mechanical properties. Additionally, the best comprehensive performance of the samples was obtained at the PEW content of 5 wt % and the CS content of 1 wt %. In addition, the effect of temperature on the shape memory properties of the samples was investigated, and the results indicate that the shape fixity ratio (Rf) and the shape recovery ratio (Rr) can reach 100% at 115 °C and 79% at 100 °C, respectively, which can contribute to the development of UHMWPE-based shape memory polymers.

Effects of graphene nanoplatelets on bio-based shape memory polymers from benzoxazine/epoxy copolymers actuated by near-infrared light

2021 ◽  
pp. 1045389X2110235
Author(s):  
Surapong Srisaard ◽  
Lunjakorn Amornkitbamrung ◽  
Krittapas Charoensuk ◽  
Chaweewan Sapcharoenkun ◽  
Chanchira Jubsilp ◽  
...  
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Near Infrared ◽  
Shape Memory Polymers ◽  
Graphene Nanoplatelets ◽  
Dynamic Mechanical ◽  
Nir Light ◽  
Uniform Dispersion ◽  
Shape Memory Properties ◽  
Shape Fixity

Novel near-infrared (NIR) light-induced bio-based shape memory polymers (SMPs) were prepared from copolymers of vanillin/furfurylamine-based benzoxazine monomer (V-fa monomer) and epoxidized castor oil (ECO). Incorporation of graphene nanoplatelets (GNPs) as photothermal fillers into the copolymers provided shape memory properties under near-infrared (NIR) light actuation. The effects of GNP content on photothermal, thermal, dynamic mechanical, morphology, and shape memory properties of the bio-based benzoxazine/epoxy copolymers (V-fa/ECO copolymers) were investigated. The results showed that the addition of GNPs significantly improved the photothermal, thermal, and dynamic mechanical properties of the copolymers. The uniform dispersion of 3 wt% GNPs in the V-fa/ECO copolymers resulted in the highest shape memory performance with shape fixity of 92% and shape recovery of 99% upon NIR light actuation. The recovery time decreased with the increment of GNP content, and the V-fa/ECO copolymers filled with GNPs displayed good execution in the repeated fold-deploy, in which the shape fixity and shape recovery values were close to the original specimen. Therefore, the outstanding properties of V-fa/ECO copolymers filled with GNPs had a potential to be excellent SMPs under NIR actuation.

Cyclic behaviors of amorphous shape memory polymers

Soft Matter ◽  
2016 ◽  
Vol 12 (13) ◽  
pp. 3234-3245 ◽  
Author(s):  
Kai Yu ◽  
Hao Li ◽  
Amber J. W. McClung ◽  
Gyaneshwar P. Tandon ◽  
Jeffery W. Baur ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Service Life ◽  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Deformation Resistance ◽  
Recovery Ratio ◽  
Loading Conditions

Cyclic loading conditions are commonly encountered in the applications of shape memory polymers (SMPs), where the cyclic characteristics of the materials determine their performance during the service life, such as deformation resistance, shape recovery speed and shape recovery ratio.

High-strain slide-ring shape-memory polycaprolactone-based polyurethane

Soft Matter ◽  
2018 ◽  
Vol 14 (22) ◽  
pp. 4558-4568 ◽  
Author(s):  
Ruiqing Wu ◽  
Jingjuan Lai ◽  
Yi Pan ◽  
Zhaohui Zheng ◽  
Xiaobin Ding
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
High Strain ◽  
Shape Memory Polymer ◽  
Polymer Networks ◽  
Ring Structure ◽  
Recovery Ratio ◽  
Ring Shape ◽  
High Deformability ◽  
Shape Fixity

To enable shape-memory polymer networks to achieve recoverable high deformability with a simultaneous high shape-fixity ratio and shape-recovery ratio, novel semi-crystalline slide-ring shape-memory polycaprolactone-based polyurethane (SR-SMPCLU) with movable net-points constructed by a topologically interlocked slide-ring structure was designed and fabricated.

Shape Recovery Characteristics of Shape Memory Polymers Subjected to Bending

2013 ◽  
Vol 834-836 ◽  
pp. 160-164 ◽  
Author(s):  
Tao Zhou ◽  
Hui Feng Tan ◽  
Yu Yan Liu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Recovery Ratio ◽  
Thin Sample ◽  
Ratio Measurement ◽  
Series Of Experiments ◽  
Finite Bending ◽  
Important Basis

Shape recovery is a critical characterization of the Shape Memory Polymers (SMP); so far, there has not been a set of uniform specifications, however, on the deformation recovery characterization of SMP, more exactly, on the shape recovery ratio measurement. A simple and effective experimental method is designed to obtain the shape recovery ratio of SMP; and a series of experiments are carried out to measure the shape recovery ratio of a thermoset shape-memory epoxy resin within the finite bending deformation at various test temperatures. And the results show that the shape recovery ratio and rate of the thin sample are larger than that of the thick one; the deformation curvature has little effect on the shape recovery ratio with the test temperatures over, or below, the glass-transition temperature,Tg, but has significant effect nearTg. The conclusions provide an important basis for the structural design of SMP.

Preparation of porous structures with shape memory properties from biodegradable polymeric networks

2012 ◽  
Vol 1403 ◽  
Author(s):  
Shahriar Sharifi ◽  
Sebastien Blanquer ◽  
Dirk W. Grijpma
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Soft Tissues ◽  
Shape Memory Polymers ◽  
Porous Structures ◽  
Trimethylene Carbonate ◽  
Polymeric Networks ◽  
Shape Memory Properties ◽  
Crosslinked Networks ◽  
Shape Fixity

ABSTRACTPreparing porous biodegradable structures from shape memory polymers can combine the structure-defining properties of porous structures with the minimally invasive implanting possibilities of shape memory polymers. In this study, porous biodegradable shape memory structures were prepared using photo-crosslinked networks based on poly(D,L-lactide-co-trimethylene carbonate). The characteristic shape memory properties of the structures, such as their shape fixity at a low temperature of 0 oC and their full shape recovery upon heating to physiological temperatures, were excellent. This makes these biodegradable and biocompatible structures very well-suited for use as self-deploying implants in medical applications like tissue engineering, drug delivery and the support of soft tissues.

scholarly journals Water Triggered Shape Memory Materials

2013 ◽  
Vol 3 (1) ◽  
pp. 49-50 ◽  
Author(s):  
Guoguang Niu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Electrical Current ◽  
Light Illumination ◽  
Poly Ethylene Glycol ◽  
Thermally Induced ◽  
Permanent Shape ◽  
Poly Ethylene ◽  
Novel Strategy

The term "shape memory effect" refers to the ability of a material to be deformed and fixed into a temporary shape, and to recover its original, permanent shape upon an external stimulus (1). Shape memory polymers have attracted much interest because of their unique properties, and applied tremendously in medical area, such as biodegradable sutures, actuators, catheters and smart stents (2, 3). Shape memory usually is a thermally induced process, although it can be activated by light illumination, electrical current, magnetic, or electromagnetic field (4-6). During the process, the materials are heated directly or indirectly above their glass transition temperature (Tg) or the melting temperature (Tm) in order to recover the original shape. Non-thermally induced shape memory polymers eliminate the temperature constrains and enable the manipulation of the shape recovered under ambient temperature (7, 8). Herein, we report a novel strategy of water induced shape memory, in which the formation and dissolution of poly(ethylene glycol) (PEG) crystal is utilized for the fixation and recovery of temporary deformation of hydrophilic polymer. This water-induced shape recovery is less sensitive to temperature, of which 95% deformation is fixed in circumstance and over 75% recovery is reached even at 0 oC.

scholarly journals A Large-Deformation Theory for Thermally-Actuated Shape-Memory Polymers and its Application

2010 ◽  
Author(s):  
Shawn A. Chester ◽  
Vikas Srivastava ◽  
Claudio V. Di Leo ◽  
Lallit Anand
Keyword(s):  
Glass Transition ◽  
Shape Memory ◽  
Deformation Theory ◽  
Shape Recovery ◽  
Large Deformations ◽  
Shape Memory Polymers ◽  
The Body ◽  
Thermally Induced ◽  
Thermally Actuated ◽  
Common Shape

The most common shape-memory polymers are those in which the shape-recovery is thermally-induced. A body made from such a material may be subjected to large deformations at an elevated temperature above its glass transition temperature &Vthgr;g. Cooling the deformed body to a temperature below &Vthgr;g under active kinematical constraints fixes the deformed shape of the body. The original shape of the body may be recovered if the material is heated back to a temperature above &Vthgr;g without the kinematical constraints. This phenomenon is known as the shape-memory effect. If the shape recovery is partially constrained, the material exerts a recovery force and the phenomenon is known as constrained-recovery.

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