Shape Memory Polymer

Shape Memory Polymers (SMPs) are polymer materials which may be returned from a deformed state to their original shape or "permanent configuration" via an external stimulus. The external stimulus is usually temperature, as in the case of thermally activated SMPs, but can also be the application of an electric or magnetic field, light or a change in pH. An SMP is an example of a smart material. Projected applications include self-adjusting orthodontic wires and selectively pliable tools for small scale surgical procedures where metal-based shape memory alloys such as Nitinol are widely used. Additional applications include self-repairing structural components, such as automobile fenders in which dents are repaired by application of heat. [Brennan, Mairin "Chemical and Engineering News", 2001, "79", p. 5 ]

Shape memory polymers differ from shape memory alloys [Czichos H. Adolf Martens and the Research on Martensite. The Martensitic Transformation in Science and Technology (Ed. E. Hornbogen & N. Jost). pp 3–14, Informationsgesselschaft (1989)] in that a glass transition from a hard to a soft phase is responsible for the effect rather than metallic Martensitic/Austenitic transitions.

Polymers with shape memory have both a visible, current form and a stored, permanent form. Once the latter has been produced by conventional methods, the material is molded into a second, temporary form by skillful heating, deformation, and finally, cooling. The plastic maintains this shape until the permanent form is recalled by a predetermined external stimulus. The secret behind these materials lies in their molecular network structure, which contains meltable "switching segments." Raising the temperature activates the switching: the crystallized switching segments melt and the material resumes its original form. The materials is effectively visco-elastic [Tobushi. H., Hashimoto T., Hayashi S. & Yamada E. Thermomechanical Constitutive Modeling in Shape Memory Polymer of Polyurethane Series. Journal of Intelligent Material Systems and Structures. Vol 8, Technomic (August 1997)] and many models and analysis methods exist.

After an undesired deformation, such as a dent in the fender, these plastics "remember" their original shape. Heating them both improves and activates their "memory." In this way, the dent could then be removed with a hair-dryer, for example. In this case, the important form is its undamaged original shape. The impact results in a temporary form, which changes back to the original form upon heating -- in effect, the plastic repairs itself.

One of the first conceived industrial applications was in robotics [Monkman. G.J. & P.M. Taylor ‑ Memory Foams for Robot Grippers ‑ Robots in Unstructured Environments ‑ Proc. 5th Intl. Conf. on Advanced Robotics, pp. 339‑342, Pisa, June 1991] where shape memory foams were used to provide initial soft prehension in gripping which could be subsequently hardened by cooling making a shape adaptive grip. Since then the materials have seen widespread usage in the building industry (foam which expands with warmth to seal window frames), sports wear (helmets, judo and karate suits) etc. and in some cases with thermochromic additives for ease of thermal profile observation [Monkman. G.J. - Advances in Shape Memory Polymer Actuation - Mechatronics - Vol 10, No. 4/5, pp. 489–498 - Pergamon June/August 2000] .

External links

* [http://www.mnemoscience.com mNEMOSCIENCE]
* [http://www.ctd-materials.com/products/emc.htm TEMBO Shape Memory Polymer]
* [http://www.crgrp.net/veriflex.htm Veriflex Shape Memory Polymer]
* [http://memorypolymer.net/ Memory Polymer News]

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Polymer — Appearance of real linear polymer chains as recorded using an atomic force microscope on surface under liquid medium. Chain contour length for this polymer is 204 nm; thickness is 0.4 nm.[1] A polymer is a large molecule (macromolecule …   Wikipedia

  • Memory-Metall — Formgedächtnislegierungen (FGL, engl. shape memory alloy, SMA) werden oft auch als Memorymetalle bezeichnet. Dies rührt von dem Phänomen, dass sie sich an eine frühere Formgebung trotz nachfolgender starker Verformung scheinbar „erinnern“ können …   Deutsch Wikipedia

  • Memory Metall — Formgedächtnislegierungen (FGL, engl. shape memory alloy, SMA) werden oft auch als Memorymetalle bezeichnet. Dies rührt von dem Phänomen, dass sie sich an eine frühere Formgebung trotz nachfolgender starker Verformung scheinbar „erinnern“ können …   Deutsch Wikipedia

  • Memory foam — is polyurethane with additional chemicals increasing its viscosity and density. It is often referred to as visco elastic polyurethane foam, or low resilience polyurethane foam (see LRPu). Higher density memory foam softens in reaction to body… …   Wikipedia

  • Polymer nanocomposite — Polymer nanoscience is the study and application of nanoscience to polymer nanoparticle matrices, where nanoparticles are those with at least one dimension of less than 100 nm. Contents 1 Nanopolymers 2 Bio hybrid polymer nanofibers 2.1 Bio… …   Wikipedia

  • Synthetic biodegradable polymer — Many opportunities exist for the application of synthetic biodegradable polymers in the biomedical area particularly in the fields of tissue engineering and controlled drug delivery. Degradation is important in the biomedical area for many… …   Wikipedia

  • Formgedächtnis-Polymer — Formgedächtnis Polymere (FGP) sind Kunststoffe, die einen Shape Memory Effekt aufweisen, also sich an ihre frühere äußere Form trotz einer zwischenzeitlichen starken Umformung scheinbar „erinnern“ können. Die ersten Formgedächtnis Polymere… …   Deutsch Wikipedia

  • Efecto térmico de memoria (polímeros) — Saltar a navegación, búsqueda El efecto unidireccional de memoria térmicamente inducido es un efecto clasificado dentro de los nuevos materiales llamados inteligentes. Los polímeros con efecto térmico de memoria son materiales nuevos, cuyas… …   Wikipedia Español

  • Composite material — A cloth of woven carbon fiber filaments, a common element in composite materials Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent …   Wikipedia

  • PEEK — For other uses, see PEEK (disambiguation). PEEK Density 1320 kg/m3 Young s modulus (E) 3.6 GPa Tensile strength (σt) 90 100 MPa Elongation @ break 50% …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.