Whats the name given to plastics that melt when heated but return to their former state when cooled?

And an example type would be nice

Thanks

Chris

Thermoplastic's
Dunno what your looking for by way of an example though

I hate it when we get homework

perspex is a plastic which melts when heated but only to the point where its bendy and stuff, but it can only be heated once from what i remember at school

perspex is a plastic which melts when heated but only to the point where its bendy and stuff, but it can only be heated once from what i remember at school

http://en.wikipedia.org/wiki/Thermoplastic

These Bad Boy's

After my extensive research (on google) thermoplastics are set by heat but don't then melt again.

Ffrench, see me at break

Cheers

Chris

oops double post!

[Edited on 21/11/08 by chrisg]

thermoplastic

polypropylene , ABS , Polycarbonate , PVC , can all be melted then formed into shapes and then set when cooled - if your asking for something thats got a memory after all that has happened , please give it to me - i wouldnt mind winning the nobel peace prize for science

My credit card

So nothing exists that can be melted, made into, say, a cup and then re-melted and made into a saucer?

Interesting

Cheers

Chris

What about this stuff? Is it something like this you're after?

Phil

That's interesting Phil, I could with finding out the chemical name is.

Thanks All

Cheers

Chris

so basically you're after a plastic with the properties of wax, for example?

yes

In a word.

Cheers

Chris

Thermoplastics, eg ABS (Acrylonitrile butadiene styrene), can be ground up and reused to make other item.

The difference between thermoplastics and thermosetting plastics is that thermoplastics become soft, remoldable and weldable when heat is added. Thermosetting plastics however, when heated, will chemically decompose, so they can not be welded or remolded. On the other hand, once a thermosetting is cured it tends to be stronger than a thermoplastic.

Some more info

Phil

AFAIK thermoplastics can be melted and re-melted although there is some loss of properties.

Thermosetting plastics can not be re-melted.

Could be wrong of course.

Thanks for that chaps, at last I'm getting somewhere, this place is the best!

I'll email those companies, see if that stuff is suitable for what I want.

Cheers

Chris

what do you actually want it for?

I could tell you, but I'd have to kill you!

It's for a recycling project, a study into using more re usable products in car body panels.

Cheers

Chris

does that mean i have to be killed now?
i didn't even get the choice!

Nah, you're safe enough.

(foir now)

Cheers

Chris

I thought it was thermoplastics (like yoghurt pots)....

quote:

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Originally posted by chrisg
I could tell you, but I'd have to kill you!

It's for a recycling project, a study into using more re usable products in car body panels.

Cheers

Chris

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Lots of info on British Plastics Federation website- thermoplastics can be heated up and cooled down lots of times in theory. Doesn't always work with the vac former!

Themosetting is a one way (chemical process), think araldite and epoxy resins, brittle electrical fittings that shatter when dropped etc

The cup and saucer can be recycled and re used in injection moulding process if made from the usual thermoplastics already listed

As a bit of an aside but partly of relevance have you had a look at polymorph - Rapid Electronics sell it as well as others - plastic granules come in a bag, pour on boiling water, it goes all soft you then mould / shape / and it cools and sets solid.

Also have a look at the TEP site from Middlesex Uni - full of useful stuff including Smart materials and some plastic with a memory

quote:

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Would you have to park in the shade in the summer (assuming we have one!)

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I bought some plastic of the bay of e which became mouldable when left in boiling water and set hard when cool, it could be softened time and time again using the same method

The name of it was polymorph

Yep, I've used polymorph extensively over the last couple of years!

Great stuff and as hard as you can imagine when cold but amazingly supple when softened in boiling water.

Example in below link!

http://cgi.ebay.co.uk/100g-Polymorph-Thermoplastic-Moulding-Compound-100g_W0QQitemZ300226021255QQcmdZViewItemQQptZUK_Crafts_Other_Crafts_EH?hash=item3 00226021255&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A1|240%3A1318

Comes in granule form and can be heated and reused, that's the one. Google it and it comes up on ebay.

Lightweight chassis so if you have a crash they can heat it up and form it into a stretcher?

Or a coffin?

I've been looking at the suggested materials and they all seem to be more suited to "blocks" of material rather than "sheets" which you would need for body panels.

The ideal would be a plastic which is used in packaging etc that could be made into body panels by melting and reforming, then it would be better from a recycling point of view.

Maybe looking for something which doesn't exist, now where's that chemistry set I got for my 10th birthday?



Cheers

Chris

We use various grades of polyethylenes and polypropylenes where I work - injection moulded packaging products. For some products, we'll re-grind the left over sprues and mould this material again into good parts. Anything we cant use again such as purgings are taken away by Plasgran, bit more info on their website. http://www.plasgranltd.co.uk/

The parts we make are fairly small, all less then 100mm in diameter so I don't know how good these materials would be in sheet form for making larger body panels.

cheers
Lee