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Metzger, Melodie F.; Wilson, Thomas S.; Schumann, Daniel L; Matthews, Dennis L; Maitland, Duncan J.

doi:10.1023/a:1014674912979

Cited by 142 publications

(50 citation statements)

References 10 publications

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“…MTS experiments were performed at two temperatures relevant to a medical device functionality: 378C (body temperature) and 808C (actuation temperature). Previous studies reported by our group 4 have shown that temperatures of T g 6 208C are well into the glassy and the rubbery plateau respectively. Elongation to failure, stress recovery cycles, and free recovery cycles were studied at maximum strains of 20 and 100%, which are reasonable ranges of deformation expected in medical device actuation.…”

Section: Introductionmentioning

confidence: 55%

“…2 In the medical field, new SMPs with adjustable moduli, high recovery ratios, sharp and adjustable transition temperatures, and biocompatible drug-eluting surfaces have enabled their use in a variety of new applications. Specifically, SMPs are currently being researched for applications in aneurysms embolization, 3 as clot extraction devices, [4][5][6] and for vascular stents. 7,8 Because of their different mechanical properties above and below the glass transition temperature, the properties of heat activated SMPs can be optimized to offer both the flexibility, the resistance in compression, and the high shape recovery needed for proper insertion, positioning, deployment, and functionality of these devices.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Shape‐memory behavior of thermally stimulated polyurethane for medical applications

Baer

Wilson

Matthews

et al. 2006

J of Applied Polymer Sci

145

108

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Shape memory polymers (SMPs) have been of great interest because of their ability to be thermally actuated to recover a predetermined shape. Medical applications in clot extracting devices and stents are especially promising. We investigated the thermomechanical properties of a series of Mitsubishi SMPs for potential application as medical devices. Glass transition temperatures and moduli were measured by differential scanning calorimetry and dynamic mechanical analysis. Tensile tests were performed with 20 and 100% maximum strains, at 37 and 808C, which are respectively, body temperature and actuation temperature. Glass transitions are in a favorable range for use in the body (35-758C), with high glassy and rubbery shear moduli in the range of 800 and 2 MPa respectively. Constrained stress-strain recovery cycles showed very low hysteresis after three cycles, which is important to know for preconditioning of the material to ensure identical properties during applications. Isothermal free recovery tests showed shape recoveries above 94% for MP5510 thermoset SMP cured at different temperatures. One material exhibited a shape fixity of 99% and a shape recovery of 85% at 808C over one thermomechanical cycle. These polyurethanes appear particularly well suited for medical applications in deployment devices such as stents or clot extractors.

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Section: Introductionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Shape‐memory behavior of thermally stimulated polyurethane for medical applications

Baer

Wilson

Matthews

et al. 2006

J of Applied Polymer Sci

145

108

View full text Add to dashboard Cite

show abstract

“…[1][2][3] The capacity of shape-memory polymers to transition between different physical shapes has led to a myriad of proposed minimally invasive biomedical applications [4] including sutures, [5] vascular stenting and repair, [6][7][8][9][10] stroketreating devices, [11,12] and microfluidic delivery devices. [13] Almost all of the proposed biomedical devices rely on large strain deformation at elevated temperatures.…”

mentioning

confidence: 99%

Deformation Limits in Shape‐Memory Polymers

et al. 2008

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Shape-memory polymers are mechanically active materials designed to store a temporary deformed shape and subsequently recover a pre-programmed permanent shape upon exposure to external stimuli such as temperature or light. [1][2][3] The capacity of shape-memory polymers to transition between different physical shapes has led to a myriad of proposed minimally invasive biomedical applications [4] including sutures, [5] vascular stenting and repair, [6][7][8][9][10] stroketreating devices, [11,12] and microfluidic delivery devices. [13] Almost all of the proposed biomedical devices rely on large strain deformation at elevated temperatures. Despite the importance of large strain deformation in a useful shape-memory effect, work has not been performed to systematically understand the strain limits in shape-memory polymer networks as a function of network structure or relevant deformation parameters. Embedded in the use of shape-memory polymers for biomedical applications is their large-strain deformation response at various characteristic temperatures, often spanning multiple material states. The objective of this paper is to understand the relationships between strain to failure, temperature, and polymer structure in biocompatible shape-memory polymer networks.Researchers have examined thermomechanical strain storage and recovery couplings in a variety of shape-memory polymers. [6,[14][15][16][17] The standard approach is to deform the polymer at a temperature (T d ) typically above material's transition temperature (T trans ), which may be a characteristic melting or glass transition temperature (T m or T g ). Once the appropriate level of deformation is obtained, the polymer is held at the imposed strain and cooled under constraint to a temperature adequately below T trans . The material is then stored at a temperature (T s ) below the transition temperature indefinitely. When recovery is desired, the stored polymer is heated from T s and strain recovery occurs through a time and temperature dependent recovery process. Free strain recovery is performed without any external constraint, while constrained stress recovery is performed in the presence of fixed strain constraint. Shape storage and recovery are rooted in the viscoelastic nature of polymer networks. Consequently, the free and constrained recovery behaviors have been shown to depend strongly on T d and the recovery temperature (T r ) relative to the glass transition. [6,14] In addition, the recovery behavior is strongly influenced by the applied stress state stored in the polymer (tension versus compression) due to the influence of thermal expansion. [15] These prior studies have built a foundation to understand the complex thermomechanical behavior of shape-memory polymers, including the storage and recovery of stress and strain as a function of time, temperature, and constraint.Despite the growing base of knowledge on the constitutive response of shape-memory polymers, minimal work has focused on the link between polymer structure, temperature, and deform...

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“…Under body heat, CHEM foams can be precisely deployed and recover a much larger predetermined required shape when in satisfactory position [126]. A CHEM foam porosity can be adjusted to the needs of the application.…”

Section: Types Of Medical Devicesmentioning

confidence: 99%