apprentice001
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Distinguish Polyvinylchloride from latex/natural rubber?
Is there a simple chemical test whereby one can differentiate and sort out which is which if they were all jumbled together? Something like a
chemical immersion separation apparatus?
I have PVC pellets mixed in with Latex pellets and would like to separate them.
Thx in advance for any help. Much appreciated!
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not_important
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It does sound as if you want a test, but a process.
look at http://www.plasticsusa.com/specgrav2.html to see densities, unfilled PVC may be lighter than natural rubber but there is some overlap. Filled
plastics are a guess, depends on what the filling is and how much was used.
If you want a test, heat a length of heavy copper wire, rub the tip of it on a pellet so as to coat it with plastic, then put the wire back in the
flame. The chlorine in PVC results in a brief blue-green colouration from copper, rubber won't do that. Also hot PVC will smell different than
rubber, which will smell like ... burning rubber.
I suspect you will need to identify a reasonable number of PVC and rubber pellets, leaving them mostly intact, then try to determine the specific
gravity of each group.
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apprentice001
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Thanks for the reply. Ive got over 1 ton of the stuff all mixed together. It would be a major pain to have to hire a guy and sift through all those
pellets not to mention he would probably go insane after a few kilos of sorting.
I only realized there were rubber in the mix when it went through my injection machine. The finished product had little warts popping out of the skin.
And those warts were the rubber pellets that did not melt. It was a real pain having to pop/pick them out.
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12AX7
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Hmm, that's a pain!
How much does a ton of plastic cost, anyway? Is it worth seperating?
Maybe you can floatation seperate them-- does the PVC float in water? If it doesn't, you could add fine sand (while stirring to keep everything
suspended) to increase the water's density. You would then have to skim the plastic beads, wash the sand off and dry it. I wonder if water content
is a problem in injection molding?
Tim
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not_important
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That was why I pointed `m at the table of densities. The problem is that "PVC" can be pure PVC, with plasticisers, or plasticisers plus filler; which
gives a range of densities from less to greater than pure rubber - which also can be filled. The only way to know would be to isolate a few grams
worth and actually measure the density - assuming that the PVC is of a uniform type.
Adding sand won't do, it would take picking a salt that is soluble enough and dense enough to give the needed value. There's tables of densities of
water-salt pairs that would help pick which to use.
I know that high DC voltages have been used to separate some types of plastics, ah - here
http://ec.europa.eu/research/industrial_technologies/impacts...
http://waste.environmental-expert.com/resultEachPressRelease...
And this outfit uses a solvent-based approach
http://www.vinyloop.com/
For only a ton I suspect that it is not worth doing it yourself, the set-up costs are likely to be great enough to be uneconomic for such a small
amount.
Can't screen/fiter the hot stuff has it is being injected?
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