> I knew there were at least 6 main plastic types.

No, there are two.  Thermosoftening and thermosetting plastics.  Each 
type has thousands of different molecules.


> But 10,000? Really?
 > I can imagine you could have 10,000 different compounds, with different
 > additives in them to adjust how springy or brittle they are, etc. But
 > 10,000 fundamentally different molecules? Really?

Not necessarily.  Take the simplest plastics, such polyethylene, which 
is just chains (called polymers) of ethylene molecules (called 
monomers).  Depending on the length of the chains, you will have 
different properties, hence different commercial applications.  LDPE and 
HDPE behave quite differently.

Also, if you alternate monomers in your chain, you will have different 
properties as well.  Nylon-4,6 behaves differently than Nylon-6,6 or 
Nylon-6,9.

Etc.

 > most plastics melt if you pour boiling water on them, never mind
 > heating them to *hundreds* of degrees...
>

YABAMBA.


to Google, don't you?

> (Also, if this plastic as such a high melting point, how do you mould it
> in the first place??)

You realize the technology to melt metals - which have higher melting 
points than plastics - has existed for millennia.

Also, look into "creep".  You don't need to melt it to be able to shape 
it.  Just like a blacksmith doesn't have to melt iron into a liquid to 
make horseshoes or a sword.

Finally, you *must* have come across pots and pans that have plastic 
handles.  I'm sure these don't melt everytime you boil water.

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