[arie]

Hi everyone,

May I know where I can find out the raw mat composition of a polystyrene food container?What kind of mold is used? Injection-molding?

Why it's white in color? Is there any additives, filler or colorants added?

Thank you.

[eugenedakin]

Hello arie,

Great question!

There are many different additives that can be mixed with polystyrene for various functional and esthetic purposes (changing the hardness, or colour). 

A great place to find more about this topic is at the following link:
http://en.wikipedia.org/wiki/Polystyrene

In Polystyrene's 'Pure' form, it is white in colour.

I hope that this helps.

Cheers!

Eugene

[arie]

Dear Eugene,

Thank you for your info. these websites have provide me a lot of useful info.

I'm still lack of the "RECIPE" of PS take-away lunchbox. I understand it's quite difficult to getthese P&C info, but I just want a brief info. Kindly inform me if you got any, k?

Thanks~

[eugenedakin]

Hello arie,

Unfortunately, I do not have exact recipies (most companies keep these recipies VERY confidential - example, the Coke-a-Cola formulation). 

Personally, I have been involved in many research projects that have created many types of formulations, and it requires alot of energy.

The only suggestion that I can make is for you to get a book on the specialized area and try experimenting from there.

I wish you the best.

Eugene

[arie]

I've complete my assg.
I found out that to produce the PS take-away hinged box,the raw materials are:
PS pellet (yield by suspension polymerization).....94-96%
blowing agent (g) (CFC, CO2, 1,1-difluoroethane, pentane)....4-6%
nucleating agent .....<0.25%

The nucleating agent would be put into the single screw extruder@ 150-205 C, 1000-2000psi.
Blowing agent would then be putting in using high pressure.
The homogenized PS would start foaming aft exit the die.
And then the PS foam would be pull towards cooling mandrel, rolll-up and left for >24hr for aging.
The extruded sheet would be used to thermo form into the desired product.

The PS box is white in color because in extruder, when the polymer is compressed and because the change of phases from clear amorphous stage to semi-crystallized stage.

[eugenedakin]

Hello arie,

Thank you for sharing this information with us.

I wish you the best.

Cheers,

Eugene