Presentation on theme: "Memory Wire Materials 1 piece of memory wire, hot water or hair dryer, tongs (can be purchased at Procedure 1. Write down."— Presentation transcript:
Memory Wire Materials 1 piece of memory wire, hot water or hair dryer, tongs (can be purchased at Procedure 1. Write down observations about the color, shape, and length of the metal wire. 2. Coil the metal wire around a pencil. Holding the coiled metal with tongs, observe what happens when you place the coiled wire in hot water or heat it with a hair dryer. 3. Name three ways that you think that a metal with this unusual property could be of benefit in manufacturing a new product. How does it work? Ninitol memory wire was named from the site of its discovery, the Nickel Titanium Naval Ordnance Laboratory in Ninitol has a chemical structure similar to most metals, it is crystalline, meaning the atoms are ordered in a particular pattern. The arrangement of atoms in the Ninitol is different at different temperatures which enables this material to “remember” its original shape. At room temperature, a phase called Marstenite is present, and at higher temperatures Austenite is present. Another key difference is what happens to the atoms when the metal is bent. When a normal metal is bent, planes of atoms slide long distances past one another so atoms are in a completely different place relative to their original neighboring atoms. They have no “memory” of the original atomic arrangement. In contrast, when Ninitol is bent all of the shape deformation is accommodated by a shift in local arrangement, but each atom still has the same original neighbors. When the material is heated the atoms shift back to their original positions relative to their neighbors and the wire reforms to its original shape. Is Ninitol currently being used in consumer products? Materials scientists call Ninitol a Shape Memory Alloy (SMA). Eye glasses, dental wires, and cell phones all utilize the ability of this material to be kinked or bent and still return to its original shape without permanent damage. There are potential applications in medicine as well. A stent is a tube shaped device that is inserted into arteries to keep them open. With memory wire it could be possible to fold the stent into a tiny volume so that it could be inserted in a non-invasive way. Localized heating could then be applied and the stent would unfold to its full volume. (Adapted from: Jones, G. M, Falvo, M.R., Taylor, A. R., Broadwell, B. P, Nanoscale Science: Activities for Grades 6-12, NSTA press, 2007, pg
Stain Resistant Fabric -Nanotex How does it work? Stain resistant fabrics are examples of nanotechnology- along with self cleaning paint and windows- that mimic the water- repelling “lotus effect” of some plant leaves. The surface of these leaves have nanometer sized waxy bumps that keep water and dirt from sticking to them. The fabric is made by dipping the fabric into a solution that coats it with tiny, nano-sized “whiskers.” The whiskers point outward, like peach fuzz, creating a layer of air next to the fabric. This cushioning layer keeps water and other liquids from soaking into the fabric. Water just beads up and rolls off the fabric. For variations and extensions of this activity see The University of Wisconsin’s Materials Research Center Outreach page. Materials Piece of nanotechnology stain resistant fabric (Nano-tex) Clothing made from nano-tex fabric can be found in most stores (look for stain resistant fabric with “Nano” in the name) Piece of regular fabric (100% cotton, synthetic such as polyester,or cotton/poly blend) Hydrophobic (water-hating) plant leaf such as lotus, leafy kale, brocilli, or Chinese cabbage Eye dropper Water Various stain agents such as grape juice, oil, ketchup, mustard, jelly, peanut butter, dirt Paper towels Procedure Part I: The Lotus Effect Use the eye dropper to squeeze a drop of water on the nano-tex fabric, the regular fabric, and the leaf. Describe the difference in the behavior of the water droplet. Part II: Testing Stain Resistance Add drops or small globules of stain agents on the two types of fabric. Observe. Using a wet paper towel gently blot the stain agents off the fabric. Record observations. Did the stain resistant fabric live up to its name? Was the stain resistant fabric more susceptible to certain agents? Repeat the process and now try rinsing off the stain agents with a gentle stream of water. Observe. Other properties to investigate: Compare the feel and texture of regular fabric and nano-tex fabric. Is there a difference in the wrinkle resistant properties of the two fabrics? Do the stain resistant properties of nano-tex disappear after washing it? How about after ven many washes? Does the nano-tex fabric still have stain resistant properties if the stain has set for a long time or dried?