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19 Cards in this Set
- Front
- Back
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Smart materials behave differently depending on what? |
The conditions (like temperature). |
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Give an example of a smart material. |
Nitinol |
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Describe nitinol and its 'smart' property. |
It's a metal alloy (about half nickel and half titanium) but when it's cool, it can be bent and twisted like rubber. If it's bent too far, though, it'll stay in that shape. Its 'smart' property is that it's a 'shape memory alloy' - if you heat it above a certain temperature, it'll go back to a 'remembered' shape. |
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Give two uses of nitinol. |
1) Glasses frames - if they get bent, you just need to put it in a bowl of warm water and it'll return to its shape. 2) Dental braces. In the mouth, the alloy warms and tries to return to its remembered shape, pulling the teeth gently with it. |
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What is a nanoparticle? |
A really tiny particle - 1-100 nanometers across. |
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Roughly, how many atoms do nanoparticles contain? |
A few hundred atoms. |
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What are fullerenes? |
Nanoparticles that are molecules of carbon, shaped like hollow balls or closed tubes. The carbon atoms are arranged in hexagonal rings. Different fullerenes contain different numbers of carbon atoms. |
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How similar are the properties of a fullerene compared to the pure element that it's made of? |
Their properties are very different - fullerenes has different properties from big lumps of carbon. |
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Give one use of fullerenes. |
They can be joined together to form nanotubes, which are tiny hollow carbon tubes, a few nanometers across. All the covalent bond make carbon nanotubes very strong and they can be used to reinforce graphite in tennis rackets. |
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What is nanoscience? |
The study of objects on a nanoscale - researching the uses of nanoparticles. |
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State some of the uses of nanoparticles which are being developed. |
1) They have a huge surface area to volume ratio, so they could help make new industrial catalysts. 2) Nanotubes can be used to make stronger, lighter building materials. 3) Nanotubes conduct electricity, so they can be used in tiny electric circuits for computer chips. 4) Nanomedicine is bein researched - tiny fullerenes are absorbed more easily by the body more easily than other particles. They could deliver drugs right where they're needed in the cells. |
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Strong covalent bonds hold the atoms together in long chains, but which boys determine the properties of the plastic polymer? |
The bonds between the different molecule chains determine the properties of the plastic. |
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Describe the structure of a polymer with weak intermolecular forces. |
The polymer will have individual tangled chains of polymers, held together by the weak intermolecular forces. These are free to slide over each other. |
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Describe the properties of a thermosoftening polymer. |
It does not have cross-linking between chains. The forces between chains are easy to overcome, meaning that the polymer is easy to melt. When the plastic cools, it hardens into a new shape. You can melt and remould these plastics as often as you'd like. |
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Describe the structure of a polymer with strong intermolecular forces. |
The polymer will have strong intermolecular forces between the polymer chains, which are called crosslinks. These hold the chains firmly together, so they cannot slide over each other. |
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Describe the properties of a thermosetting polymer. |
I has crosslinks. These hold the chains together in a solid structure. The polymer doesn't soften when it's heated. Thermosetting polymers are strong, hard and rigid. |
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True or false: The way that you make a polymer affects its properties. |
True. |
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Describe how LD (Low Density) polythene is made. What is it used for? |
Ethene is heated to about 200 degrees Celsius under high pressure. It's flexible and is used for bags and bottles. |
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Describe how HD (High Density) polythene is made. What is it used for? |
Ethene is heated at a lower temperature and pressure than LD polythene (with a catalyst). It's more rigid and is used for water tanks and drainpipes. |
