Shape-Memory Properties of Electrospun Non-wovens Prepared from Amorphous Polyetherurethanes Under Stress-free and Constant Strain Conditions

2012 ◽  
Vol 1403 ◽  
Author(s):  
Tilman Sauter ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Fiber Diameter ◽  
Tensile Tests ◽  
Polymer Chains ◽  
Single Fiber ◽  
Elongation At Break ◽  
Shape Memory Properties ◽  
Degree Of Orientation ◽  
Shape Fixity

ABSTRACTThe shape-memory properties of electrospun polyetherurethanes (PEU) non-wovens with a single fiber diameter of around 1 μm were explored. In uniaxial cyclic, thermomechanical tensile tests a dual-shape shape-memory creation procedure (SMCP) was applied and the shape recovery was examined under stress-free and constant strain conditions. The thermal properties of the electrospun PEU non-wovens were found to be similar to those obtained for bulk PEU samples, whereas the mechanical properties revealed differences with respect to the elongation at break (εb) at increased temperatures. Excellent dual-shape properties were achieved for the PEU non-wovens with a high shape fixity rate (Rf) and shape recovery rate (Rr). A significant higher recovery stress (σmax) was obtained under constant strain recovery conditions for the electrospun non-wovens compared to the bulk PEU samples, which might be attributed to the higher degree of orientation of the polymer chains in the microfibers. Therefore the influence of different (single) fiber diameters as well as the variation of the programming elongation εm and temperature Tprog on σmax is an interesting issue for future investigations.

Synthesis and Characterization of a Bio-Compatible Shape Memory Polymer Blend for Biomedical and Clinical Applications

2014 ◽  
Author(s):  
Janice J. Song ◽  
Jennifer Kowalski ◽  
Hani E. Naguib
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shape Memory ◽  
Recovery Rate ◽  
Shape Recovery ◽  
Clinical Applications ◽  
Poly Lactic Acid ◽  
Shape Memory Properties ◽  
Shape Fixity ◽  
Recovery Temperature

Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over existing SMP materials and are being studied extensively for biomedical and clinical applications. Polymer blending has proved to be an effective method to improve the mechanical properties of polymers (such as tensile strength and toughness) as well as shape memory properties. In this study, we investigate the effect of blending two bio compatible polymers, thermoplastic polyurethane (TPU), a polymer with a high toughness and percent elongation, and poly-lactic acid (PLA), a stiff and strong polymer. The thermal, mechanical and thermo-mechanical (shape memory) properties of TPU/PLA blends were characterized in the following weight percent compositions: 80/20, 65/35, and 50/50 TPU/PLA. The TPU/PLA SMP blending was achieved with melt-blending and the tensile samples were fabricated with compression molding. The mechanical properties of each blend were studied at three different temperatures. The following thermo-mechanical (or shape memory) properties were also studied at each temperature: the shape fixity rate (Rf), shape recovery rate (Rr) and the effect of recovery temperature on the shape memory behavior. The microstructure of the polymer blends were investigated with an environmental scanning electron microscope (SEM). The results showed that the glass transition temperatures of the blends were similar to pure PLA. The toughness of the SMP blend increased with increasing TPU concentration and the tensile strength of the blend increased with PLA composition. The shape fixity rate of the TPU/PLA blend increased with increasing TPU content and the shape recovery rate increased with increasing deformation and recovery temperature. The various TPU/PLA SMP blends characterized in this study have the potential to be developed further for specific biomedical and clinical applications.

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.

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.

Shape-Memory Properties of Nanocomposites based on Poly(ω-pentadecalactone) and Magnetic Nanoparticles

2012 ◽  
Vol 1403 ◽  
Author(s):  
M. Y. Razzaq ◽  
M. Behl ◽  
A. Lendlein
Keyword(s):  
Mechanical Properties ◽  
Magnetic Nanoparticles ◽  
Shape Memory ◽  
Shape Recovery ◽  
Weight Content ◽  
Magnetic Heating ◽  
Shape Memory Properties ◽  
Potential Applications ◽  
Alternating Magnetic Fields ◽  
Shape Fixity

ABSTRACTMagneto-sensitive shape-memory polymers (SMP) obtained by incorporating magnetic nanoparticles in a SMP matrix are an emerging class of multifunctional materials. The incorporation of the nanoparticles enhanced the mechanical properties and in addition enabled remote actuation by exposure to alternating magnetic fields. Here, we report on the thermallyinduced shape-memory properties of such magneto-sensitive nanocomposites based on poly(ω- pentadecalactone) (PPDL) switching segments and magnetic nanoparticles. A series of nanocomposites were prepared by crosslinking of poly(ω-pentadecalactone)dimethacrylate (Mn = 2800 g·mol-1and 5100 g·mol-1) in the presence of silica encapsulated magnetic nanoparticles. The silica shell of the nanoparticles was selected to enhance the distribution and compatibility of the nanoparticles with the polymer matrix. Thermal and mechanical properties of the nanocomposites were explored as a function of PPDL chain length and nanoparticle weight content. All nanocomposites exhibited excellent shape-memory properties with shape fixity rates between 86% and 93% and shape recovery rates above 97%. Potential applications for such shape-memory nanocomposites include smart implants, medical instruments, which could be controlled on demand by thermal or indirect magnetic heating.

Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment

2021 ◽  
Author(s):  
mohammad amini ◽  
Kourosh Hasheminejad ◽  
Abbas Montazeri
Keyword(s):  
Potential Energy ◽  
Surface Treatment ◽  
Shape Memory ◽  
Functional Groups ◽  
Shape Recovery ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Radius Of Gyration ◽  
Oh Groups ◽  
Shape Fixity

Abstract This paper aims to comprehend the mechanisms underlying the shape memory behavior of polylactic acid infused with graphene functionalized by four groups of -OH, -CH3, -NH2, and tethered polymer layer. Applying molecular dynamics simulation, it is revealed that the graphene surface treatment enhances the shape fixity ratio of nanocomposites monotonically by increasing the physical cross-linking points within the polymer matrix. The improvement would be even more pronounced by increasing the coverage degree of small functional groups and grafting density of the covalently bonded polymer chains. Monitoring the key parameters illustrates that contrary to the OH groups, which improve the shape recovery value, the other functional groups degrade it by prohibiting the polymer chains mobility. Attempts to explore the governing mechanism demonstrate that shape fixity is improved when the difference between the potential energy variations in the loading and unloading stages increases. Interestingly, shape recovery is only under the influence of conformational entropy, and it is not affected by the potential energy. As such, we also probe variations of the radius of gyration during the recovery stage to address the role of different functionalization procedures on the reported shape recovery parameter.

Pseudoelasticity of Cu-13.8Al-Ni Alloys Containing V and Nb

2008 ◽  
Vol 59 ◽  
pp. 101-107 ◽  
Author(s):  
Rodinei Medeiros Gomes ◽  
Ana Cris R. Veloso ◽  
V.T.L. Buono ◽  
Severino Jackson Guedes de Lima ◽  
Tadeu Antonio de Azevedo Melo
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Shape Recovery ◽  
Cold Water ◽  
Low Cost ◽  
Tensile Tests ◽  
Grain Refiner ◽  
Good Shape ◽  
Potential Applications ◽  
Superelastic Behavior

Polycrystalline copper-based shape memory alloys have been of particular interest in relation to Ni-Ti because of their low cost and good shape memory effect. Nevertheless the absence of a pronounced pseudoelasticity effect restricts the number of potential applications. In this work, the influence of Nb and V on the microstructure and the mechanical properties was investigated. Samples of Cu-13.8 Al-Ni containing V and Nb alloy were prepared by induction and solution treated at 850°C and then further quenched into cold water. The addition of Nb and V promotes the formation of precipitates which act as grain refiner and subsequently improve the mechanical properties. The tensile tests were performed at temperatures slightly inferior to Mf and superior to Af, to investigate the shape recovery and pseudoelasticity, respectively. Based on the analyses of the Cu-13,8Al-2Ni-1Nb (wt%) alloy was detected rupture strains greater than 14%, besides observation of the superelasticity of these alloys and quantification of this property by means of cycling, from 0 to strains between 1 and 7%. The studies performed on alloy Cu-13.8Al- 3,5Ni-1V (wt%) made it possible to determine rupture strains in the order of 3% and its superelastic behavior through cycling for deformations between 1 and 3%.

Characristics of Shape Memory Composites Combined with Shape Memory Alloy and Shape Memory Polymer

2013 ◽  
Vol 705 ◽  
pp. 169-172
Author(s):  
Xue Feng ◽  
Li Min Zhao ◽  
Xu Jun Mi
Keyword(s):  
Shape Memory ◽  
Room Temperature ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Young Modulus ◽  
Thermomechanical Properties ◽  
The Matrix ◽  
Shape Memory Composites ◽  
Shape Fixity

In order to develop high functionality of shape memory materials, the shape memory composites combined with TiNi wire and shape memory epoxy were prepared, and the mechanical and thermomechanical properties were studied. The results showed the addition of TiNi wire increased the Young modulus and breaking strength both at room temperature and at elevated temperature. The composites maintained the rates of shape fixity and shape recovery close to 100%. The maximum recovery stress increased with increasing TiNi wire volume fraction, and obtained almost 3 times of the matrix by adding 1vol% TiNi wire.

Origami-inspired shape memory dual-matrix composite structures

2019 ◽  
Vol 30 (17) ◽  
pp. 2639-2647
Author(s):  
O-Hyun Kwon ◽  
Jin-Ho Roh
Keyword(s):  
Shape Memory ◽  
Polymer Composite ◽  
Matrix Composite ◽  
Composite Structures ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Morphing Structure ◽  
Composite Skins

A sandwiched morphing structure is developed using an Origami-inspired shape memory dual-matrix composite core and shape memory polymer composite skins. The geometric parameters of the morphing structure are designed to have a zero Poisson’s ratio. In addition, an analytical model is developed to analyze the three-dimensional morphing structure easily. The shape memory dual-matrix composites are fabricated with woven fabrics based on the shape memory polymers, and an epoxy matrix is used to ensure a flexible and shape-recoverable structure. The shape recoverability of the shape memory polymer composite skins is verified by measuring the shape recovery ratio at various temperatures. Based on the tensile tests for the shape memory polymer composite skins and shape memory polymer hinges, it is found that the morphing structure can be highly flexible depending on temperature. Finally, the bending and shape recovery behaviors of the morphing structure are demonstrated.

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.

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