2006-12-03 04:43:28 · 4 answers · asked by brandine 1 in Science & Mathematics ➔ Chemistry
Polyethene is a tough white, translucent, waxy thermoplastic (which means it can be repeatedly softened by heating). It is a polymer of the gas ethylene (technically called ethene, C2H4). It is used for packaging, bottles, toys, wood preservation, electric cable, pipes and tubing.
Polyethylene is produced in two forms: low-density polyethylene, made by high-pressure polymerization of ethylene gas, and high-density polyethylene, which is made at lower pressure by using catalysts. This form, first made 1953 by German chemist Karl Ziegler, is more rigid at low temperatures and softer at higher temperatures than the low-density type. Polyethylene was first made in the 1930s at very high temperatures by ICI. In the UK it is better known under the trademark Polythene.
2006-12-03 05:58:19 · answer #1 · answered by nicky_bronx 3 · 0⤊ 0⤋
Ah, actually no. Thermoplastics are "reusable" polymers. Many polymers, once formed, cannot be reused--e.g., tires. Thermoplastics can simply be reheated, at which point they melt, and then reshaped into whatever other shape you want.
Shape-memory ALLOYS are a really cool set of materials that are 100% made up of metals, not organic material (polyethylene is an organic polymer). The reason they "remember" their shape is that if you deform them you are messing up their crystal structure, and they want to get back to their nice highly organized crystal structure. In the future, one day your car bumper might be made of such material. If someone accidentally bumps you or runs a shopping cart into your car in a parking lot it will simply reshape itself. You can read more about them here:http://en.wikipedia.org/wiki/Shape_memory
It is important to know that the shape memory phenomenon is exclusively an inorganic phenomenon--for materials made of metal alloys--not an organic one, i.e. nothing that starts with "poly" will have that behavior.
2006-12-03 05:29:42 · answer #2 · answered by Some Body 4 · 0⤊ 0⤋
its what it says. its polythene with memory. you heat it up, is pliable and retirns to its original shape. thermoplastics...
2006-12-03 04:52:22 · answer #3 · answered by Anonymous · 0⤊ 0⤋
yeah exactly what the guy said above me
2006-12-03 05:10:28 · answer #4 · answered by Roger S 2 · 0⤊ 0⤋