polystyrene (1 Viewer)

[Mshell]

hey, are there two types of polystyrene? what are the properties and uses?

 

[tehsky]

http://hsc.csu.edu.au/chemistry/core/identification/chem921/chem921net.html#c6

make that website one of your best friends along with google =]

 

[wrxsti]

well me thinks you should only learn one ...

Polystyrene:
Use: Foam Cups
Property: Chemically Unreactive, Heat Insulating Property, Low Denisty


They wont ask for any more...

 

[independantz]

Would they ask you to define the properties? e.g. why it's a good heat insulator.

 

[willC]

Yes! I'm pretty sure ive seen a question like that before somewhere...Foamed polystyrene is a good heat insulator as it has lots of air pockets in the bubbly bits i think....

 

[jlnWind]

hey, are there two types of polystyrene? what are the properties and uses?

There is only one polystyrene. But commercially there are two predominating types.

i) Polystyrene used in tool handles or car batter cases.
Properties:- Hardest (out of PVC, LDPE and HDPE) due to large stiffening side group (phenyl side group)
- Does not have C-Cl bonds so it is not vulnerable to UV decomposition
- Has minimal chain branching meaning it can pack closely and have a very crystalline structure adding to its hardness and rigidity.

ii) Polystyrene used in foam for packagin and cups
Properties:- Gains compressibility because of air. (Gas was bubbled into the mixture during polymerisation)
- Softness and lightness because of above ^.

Personally I don't like to use polystyrene as a foam, because i feel it doesn't necessarily address ITS chemical properties, but instead its based on the
air which provides it with compressibility. Nonetheless, both would do fine.
Enjoy.

 

[MrZ]

There are two types of Polystyrene; expanded and extruded. Expanded polysterene is white and is commonly used as a cup for hot drinks and as cushion packaging (the stuff used to package tv's and other electrical appliances). Interestingly many Sydney councils do not recycle polystyrene, which is silly as it is a popular product that can be recycled and doesn't biodagrade well in landfills. Extruded polystyrene, as the name suggests, extrudes polystyrene into particular container shapes used in the food industry. The old McDonald's polystyrene containers of the 70's and 80's (when big mac's use to cost about 60c) were examples of extruded polystyrene. Both obviously have similar low densities (good for shock absorption during transport) and thermal insulation properties. Go to http://www.r-control.com/EPS/faq.asp for more information on this subject. Band 6 Chemistry students may wish to use this information to cover dot point 9.2.1.2.8 on page 47 of the Chemistry Syllabus. Mr Z

 

[morganforrest]

I guess it depends how you define types. Both extruded (meaning you get the heated liquid polystyrene and blow air through it as it sets) and expanded result from the polymerisation reaction of ethenylbenzene. So they can be shaped in two different ways which results in them having different uses, but the base monomer and the chemical reaction for polymerisation remains the same. Extruded simply has air blown through it.