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Flashcards in C1e Deck (11):

What are the properties of polymers and their uses?

Strong/ rigid - polymers such as high density polyethene are used to make plastic milk bottles.
Light/ stretchable - low density polyethene used for plastic bags and squeezy bottles.
Durable - PVC can be rigid, for window frames and piping, or stretchy, for synthetic layer.
Protective - polystyrene foam is used in packaging to protect breakable things and to make disposable coffee cups as it's a good thermal insulator.


What are atoms in plastics held together by?

Covalent bonds.


What are the properties of plastics related to simple models of their structures?

If the plastic is made up of long chains that are held together by weak intermolecular forces, then the chains will be free to slide over each other. This means the plastic can be stretched easily, and will have a low melting point.
Some plastics have stronger bonds between the polymer chains - these might be covalent bonds between the chains, or cross linking bridges. These plastics have high melting points, are rigid and can't be stretched, as the crosslinks hold the chains firmly together.


What is nylon used in?



Compare the properties of nylon and GORE-TEX fabric?

Nylon is tough, lightweight, keeps water and UV light out but does not let water vapour through which means that sweat condenses. GORE-TEX fabrics have all the properties of nylon but is breathable.


Why has the discovery of GORE-TEX like materials been of great help to active outdoor people to cope with perspiration wetness?

If you sweat in breathable material, water vapour can escape and there is no condensation.


Why are GORE-TEX type materials waterproof and yet breathable?

GORE-TEX fabrics are made by laminating a thin film of a plastic called PTFE onto a layer of another plastic, such as polyester and nylon. This makes the PTFE sturdier. The PTFE film has tiny holes which let water vapour though so it's breathable. But it's waterproof, since the holes aren't big enough to let big water droplets through and the PTFE repels liquid water.


What are many polymers?

Non-biodegradable - they're not broken down by microorganisms, so they don't rot. They will not decay or decompose by bacterial action.


What are some of the ways that waste polymers can be disposed of?

Use of landfill sites, burning of waste polymers and recycling.


Why are chemists developing new types of polymers?

They are developing polymers that will biodegrade or dissolve because any plastic that is thrown away breaks down rather than sitting in a landfill.


What are the environmental and economic issues with the use and disposal of polymers?

In a landfill site, they will stay for ages, fill up quickly and waste land, and burning them can release poisonous gases such as acidic sulfur dioxide and it's a waste of plastic. Recycling them is the best way as they can be reused lots, but it's difficult and expensive, causing economic problems.