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Cross-linking Polyvinyl Alcohol

by SkepticJ
Tags: alcohol, crosslinking, polyvinyl
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SkepticJ
#1
Jul20-08, 02:13 AM
P: 251
Some friends and I are working on a movie, and we need a very stringy clear slime; like is produced with polyvinyl alcohol cross-linked with disodium tetraborate. Only we need it to be food-safe, so we can't simply use that. Is there another way to cross-link PVA into a stringy slime using edible chemicals?
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SkepticJ
#2
Jul30-08, 03:35 AM
P: 251
A few days ago I watched the movie Charlie and the Chocolate Factory, and therein was a slime that had pretty much the mechanical properties I'm looking for, and was edible. It wasn't transparent, but milky translucent. And green -- but that's just food coloring. What could it have been made of?

Is cross-linking polyvinyl alcohol using an edible compound just not possible, at least yet?
chemisttree
#3
Jul31-08, 11:09 AM
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It probably wasn't PVA-based. It could be any number of starches, gums or soluble polymers. Have you seen Guar gum by itself or Carageenan? How about plain Methocel or Ethocel?

GCT
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Aug1-08, 11:46 PM
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Cross-linking Polyvinyl Alcohol

OP ,

I happen know that PVA with suitable macromers in water formulation would have the properties that you've mentioned ; also you can experiment with saturating water with the PVA and perhaps PVAc in water .
SkepticJ
#5
Aug6-08, 03:04 AM
P: 251
Thanks, guys.

Re: Methylcellulose

I got some of it weeks ago, and tried it out. It's not the right texture. It's not stringy at all, but more like a yogurt.

The other stuff mentioned looks like it will work.
GCT
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Aug6-08, 09:54 AM
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Are you referring to Carboxymethyl cellulose ? From what I remember this is not exactly clear in water except at lower concentrations . It can get viscous as it is used as a lubricant .
chemisttree
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Aug6-08, 10:15 AM
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Use the methocel to provide the base viscosity and blend with an extract of boiled okra for the stringiness.
chemisttree
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Aug6-08, 10:58 AM
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I see that galactose dialdehyde can be used as a food grade crosslinker. I doubt that it is an approved compound though. The article mentions that it will crosslink protein (via the amino functionality giving schiff base type products) but aldehydes will also crosslink alcohols under acidic conditions.

Finding a food grade aldehyde that I would trust will be a problem though.
SkepticJ
#9
Aug8-08, 04:24 AM
P: 251
Quote Quote by chemisttree View Post
Use the methocel to provide the base viscosity and blend with an extract of boiled okra for the stringiness.
Ah, mucilage - brilliant idea, there.
SkepticJ
#10
Aug8-08, 04:42 AM
P: 251
Quote Quote by GCT View Post
Are you referring to Carboxymethyl cellulose ?
I don't think so, but I wouldn't rule out that being what it is. The container just says methylcellulose -- bought it from a special FX supply company.

It looks quite clear in water to me; though if I mix up a really thick batch (a ball of it will hold its shape against gravity, mostly), it's translucent.


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