Maro Publications

Auxetic Materials

From 06/04/2014 through 10/8/2013

Notes

Patent Abstracts

Patent Titles

From 06/04/2014 through 10/8/2013

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Patent Titles

10/1/2013

2. 8,545,745 
Method for using a poisson ratio material 

1. 8,544,515 
Ultralightweight runflat tires based upon negative poisson ratio (NPR) auxetic structures

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Patent Abstracts

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Notes

“Auxetics are materials that have a negative Poisson's ratio. When stretched, they become thicker perpendicular to the applied force. This occurs due to their hinge-like structures, which flex when stretched. Auxetic materials can be single molecules or a particular structure of macroscopic matter. Such materials are expected to have mechanical properties such as high energy absorption and fracture resistance. Auxetics may be useful in applications such as body armor, packing material, knee and elbow pads, robust shock absorbing material, and sponge mops.

Auxetics can be illustrated with an inelastic string wound around an elastic cord. When the ends of the structure are pulled apart, the inelastic string straightens while the elastic cord stretches and winds around it, increasing the structure's effective volume.

The term auxetic derives from the Greek word αὐξητικός (auxetikos) which means "that which tends to increase" and has its root in the word αὔξησις, or auxesis, meaning "increase" (noun). This terminology was coined by Professor Ken Evans of the University of Exeter.

Scientists have known about auxetic materials for over 100 years, but have only recently given them special attention. The earliest published example of a synthetic auxetic material was in Science in 1987, entitled "Foam structures with a Negative Poisson's Ratio" by R.S. Lakes from the University of Iowa. The use of the word auxetic to refer to this property probably began in 1991.

Designs of composites with inverted hexagonal periodicity cell (auxetic hexagon), possessing negative Poisson's ratio, were published in 1985.

Typically, auxetic materials have low density, which is what allows the hinge-like areas of the auxetic microstructures to flex.

Examples of auxetic materials include:

 Certain rocks and minerals

 Living bone tissue (although this is only suspected)

 Specific variants of polytetrafluorethylene polymers such as Gore-Tex

 Paper, all types. If a paper is stretched in an in-plane direction it will expand in its thickness direction due to its network structure.

 Tailored structures designed to exhibit special designed Poisson's ratios.”

(Auxetic Materials, Wikipedia, 10/8/2013)

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Interested!!
Bookmark this page to follow future developments!.
(RDC 7/16/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921
E-Mail: cornelrd@bee.net  

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Copyright 2013 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 10/8/2013.