Shape Memory Rubber…

Shape-memory rubber may create new avenues in market  ROCHESTER, N.Y.—Researchers at the University of Rochester have developed shape-memory rubber that won’t crystallize and will allow engineers to control the speed at which the material returns to its original shape, which means it can hold its shape for an extended time period.

The new material may lend itself to numerous applications such as biomedical implants, self-sealing sutures, “smart” labels and safety face masks or gas masks that conform to an individual’s features. Mitchell Anthamatten, an assistant professor of chemical engineering at the University of Rochester in New York, is the lead inventor.

The co-inventor is Jiahui Li, the lead author of an article, “Shape-Memory Effects in Polymer Networks Containing Reversibly Associating Side-Groups,” which appeared recently in the journal “Advanced Materials.”

Also on the project team were Michelle H. Wrue, a graduate student, and James A. Viveros, who was an undergraduate student while the project was under way.

“We’ve been toying around with this idea for several years,” Anthamatten said. “We designed the material in order to observe the (shape-memory) effect, and we were fortunate because the effect was indeed strong.” The research was partially supported by the American Chemical Society Petroleum Research Fund and a Horton Fellowship.

Anthamatten described shape-memory polymers as materials that can be deformed mechanically, and then cooled while they are under the stress of being deformed.

Cooling or freezing allows them to hold their temporary shape. But previous versions of shape-memory polymers crystallize when cooled, or turn to “polymer glass” and become brittle.

He said the University of Rochester team´s material can be called shape-memory rubber rather than a polymer. The material utilizes the dynamics of hydrogen bonding to stabilize the temporary shape, which enables this material to remain soft, flexible and rubbery while holding its shape.

The material also is transparent, while traditional shape-memory polymers are opaque when cooled. Anthamatten stressed that he is not an applications expert and can only suggest possible uses for this material.

He said the new polymers might be used in “smart” labels—labels that can change color or coding to indicate, for example, the age or temperature history of food products or prescription medications. In this possible application, shape-memory rubber could function as a “gate,” enabling dye molecules to diffuse on the label—or halting them—depending on a product’s age or the temperature at which it has been kept.

For example, consumers could tell whether the milk they buy has been held at the proper temperature since it was bottled.

“I’m excited about that potential application,” he said. “You’d have a label that indicates to the consumer whether a product is too old to use.”

Anthamatten explained that the hydrogen bonding dynamics used in this material involve a noncovalent interaction. The bonds are dynamic—bonds form, then break, then new bonds are formed. Low-temperature bonds are long-lived. At high temperatures, they are shorter-lived.

The temperature of the human body—98.6° F—would be considered an intermediate temperature for these bonds, he said, so if the material can be used for implants, it would enable doctors to insert them through a small incision, then the devices would expand gradually to the desired size and shape.
Source:
http://www.rubbernews.com/subscriber/headlines2.html?id=1203020181

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Since 1971 Redwood Plastics and Rubber has worked directly with customers to find solutions for a variety of problems including shock, abrasion, noise, wear, & friction. In partnership with our manufacturing divisions, Redwood Plastics and Rubber molds, machines, and fabricates a wide-range of high quality, custom components. Our dedication to ethical and respectful interaction with our customers, suppliers and each other is the key to our long standing relationships. Relationships that are enabled by the pride, enthusiasm and commitment of each member of our organization.

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