Sciencemadness Discussion Board

DIY Plastic

elementcollector1 - 20-6-2013 at 21:03

I'm trying to find a way to cast a clear or translucent plastic at home for a project. So far I've considered bioplastic (a mix of glycerine, water, starch and vinegar), Optix / Plexiglas(polymethyl methacrylate), and de-aerated (for lack of a better word) Styrofoam through the use of acetone (though oddly enough, this didn't work when I tried it 5 minutes ago).
Is there any other method of creating a castable/moldable translucent plastic that anyone would like to share? I was also tempted to melt regular plastic bottles, but the fumes and decomposition and final opacity (faster cooling = more transparency) are three things I would not much like to deal with.
Ideas?

franklyn - 20-6-2013 at 23:52

Sugar with minimal water can be boiled and poured to congeal into a
translucent clear material that is very brittle after it hardens. Master
desert chefs do this all the time.

Melting plastic bottles of the same material is as cheap as it gets.
just beware the risk of flaming napalm when it is melted.

Pieces of Plexiglass can be joined by wetting with methylene chloride.

A can of clear finish polyurethane varnish can be painted on a substrate
such as a plastic sheet forming a strong flexible composite. A mold form
can be repeatedly dipped and dried to achieve thickness.

Castable acrylics are available but are the most expensive solution.

.

Dr.Bob - 21-6-2013 at 06:20

The two simplest methods are 1) a 2 part epoxy plastic, which will work OK, especially if it is designed for that purpose (designed to be a clear plastic) and 2) just distilling methyl methacylate from acrylic scraps (it depolymerizes upon heating) and then pouring it over the item to encase and allowing it to sit a while (or adding a trace of a free radical initiator, eg an organic peroxide). Be warned that methyl methacylate is smelly and toxic, so that is best done outside. It will also coat your glassware in polymeric goo, so use old glassware.

elementcollector1 - 21-6-2013 at 08:12

Quote: Originally posted by Dr.Bob  
2) just distilling methyl methacylate from acrylic scraps (it depolymerizes upon heating) and then pouring it over the item to encase and allowing it to sit a while (or adding a trace of a free radical initiator, eg an organic peroxide).

I don't quite get it - this forms a mold, or the object itself?
If I had a mold, and poured the distilled methyl methacrylate into the mold, wouldn't it harden back into the shape of the mold (making a perfect casting)?
I hope there's some way to get rid of this gunk - otherwise this sounds promising!

ScienceSquirrel - 21-6-2013 at 08:23

If you do not mind using ready made plastic precursors this is very effective;
http://www.easycomposites.co.uk/Products/silicone-mould-resi...

When I was a lad these were sold as toys for teenagers but I suspect the Health and Safety elf has knocked that on the head! :(

bfesser - 21-6-2013 at 08:33

<strong>elementcollector1</strong>, have you considered <a href="http://en.wikipedia.org/wiki/Glyptal" target="_blank">glyptal</a> <img src="../scipics/_wiki.png" /> resin? I thought there was a procedure for it in Pavia or Williamson, but I can't seem to find it. Here's <a href="http://uncw.edu/chem/documents/SynthesisofPolymers.pdf" target="_blank">something</a> <img src="../scipics/_ext.png" /> from a quick google search. I performed a similar preparation once, with good results. I used disposable culture tubes and an open flame, rather than watch glasses. You should be able to pour and mold it while it's hot.

[edit]
Found the entry in my old lab notebook. Here's a summary:
- 0.10 g anhydrous sodium acetate + 2.00 g phthalic anhydride into each of two 15 x 85mm culture tubes
- 0.80 ml ethylene glycol and 0.80 ml glycerol added to tubes (one alcohol each) along with wooden applicator to prevent bumping/facilitate stirring
- preparations were made to collect any noxious vapors (phthalic anhydride sublimes readily)
- heated each tube with open flame until reactants fused/dissolved into homogeneous mixture
- once gas evolution (H<sub>2</sub>O) was observed, heating was continued for 5 minutes
"- after cooling, the ethylene glycol tube contained a viscous clear polymer resin
- the glycerol tube contained a clear hard resin which resembled soft amber (coloration due to the wooden stick which could no longer be removed)&mdash;this is 'glyptal' resin
- the ethylene glycol-based resin dissolved readily in distilled H<sub>2</sub>O"

Sorry, my note-taking wasn't particularly good at the time. I did, however cite a reference in my notebook. It was indeed based upon a procedure from Pavia.

<a href="http://books.google.com/books/about/Introduction_to_organic_laboratory_techn.html?id=SMMxAAAAMAAJ" target="_blank"><em>Procedure 36A &ndash; Polyesters</em>. <strong>Intro. to Org. Lab. Techniques: a contemporary approach</strong>. Pavia, Lampman, Kriz. 1976. Pages 282-283.</a> <img src="../scipics/_ext.png" />

[Edited on 7/9/13 by bfesser]

elementcollector1 - 21-6-2013 at 08:43

This also sounds promising, as I can buy antifreeze and distill it easily.
As for the phthalic acid, that is much harder. Phthalic anhydride is apparently "A widely distributed commodity chemical", but I can't seem to find any OTC sources for it...

EDIT: I've seen and worked with similar things as to that silicone molding package, and have a source lined up on Amazon - but I'd like to see if there's something cheaper in the cards.

[Edited on 21-6-2013 by elementcollector1]

bfesser - 21-6-2013 at 09:02

I purchased 500 g of phthalic anhydride from <a href="http://www.chemsavers.com/" target="_blank">Chemsavers</a> <img src="../scipics/_ext.png" />, back when they were just an eBay seller. It had visible impurities, but that's no problem for this compound. I'm not sure about them now, though. Perhaps someone else can advise you on this.

It's important to note that the anhydride can easily be prepared by heating the acid (loses water), the acid can easily be recrystallized from the anhydride by boiling in water, and the anhydride is readily sublimed. So, in essence, finding either is like finding both; <em>and</em> it's one of the simplest organics to purify, in my experience.

Note: Please see my earlier response; I've edited it.

[Edited on 7/9/13 by bfesser]

watson.fawkes - 21-6-2013 at 09:03

Quote: Originally posted by bfesser  
<strong>elementcollector1</strong>, have you considered <a href="http://en.wikipedia.org/wiki/Glyptal" target="_blank">glyptal</a> <img src="../scipics/_wiki.png" /> resin?
Glyptal is a trademark for a commercial product. It's originally a contraction of "glycerol-phthalate" (or the like), as I recall. I made a post here on this material a few years ago, but it seems to have vanishes. See this page for commercial varnishes. I believe this is the manufacturer; there are many distributors. The clear one is GLY1202. The one with red iron oxide is GLY1201, used both as a high voltage insulator as well as a vacuum system sealant.

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: fixed broken image(s)]

[Edited on 7/9/13 by bfesser]

elementcollector1 - 21-6-2013 at 13:49

I guess I should mention that the point of all this was to create a peculiar shape that would 'light up' evenly from a few colored LED's - hence the translucency and not transparency. I can get moderate results by sanding my Plexiglas, but wanted to know if there was an easier/cheaper solution.
EDIT: Something like these (actually, exactly like these).






[Edited on 21-6-2013 by elementcollector1]

watson.fawkes - 21-6-2013 at 14:48

Quote: Originally posted by elementcollector1  
I guess I should mention that the point of all this was to create a peculiar shape that would 'light up' evenly from a few colored LED's
Hot glue. No joke; higher quality formulations are used for potting high voltage circuits.

elementcollector1 - 21-6-2013 at 15:06

Amazingly, that's probably the best idea I've heard all day - but how would one prevent it from sticking to the mold? It is glue, after all.

bfesser - 21-6-2013 at 17:56

Hot glue doesn't adhere to polished surfaces. Just wait for it to cool and peel away.

You're building a <a href="https://en.wikipedia.org/wiki/Gravity_Gun#Half-Life_2_gravity_gun" target="_blank">Half-Life 2 gravity gun</a> <img src="../scipics/_wiki.png" /> prop?

<a href="http://www.ubergizmo.com/2012/01/half-life-2-gravity-gun-prop-21000-auction/" target="_blank"><img src="http://cdn2.ubergizmo.com/wp-content/uploads/2012/01/17-Half-Life-2-Gravity-Gun-prop.jpg" width="300" /></a> <img src="../scipics/_ext.png" valign="top"/>

[Edited on 15.2.14 by bfesser]

elementcollector1 - 21-6-2013 at 19:18

Yes indeedy, and I see you know the source!
I'd have to buy a lot of hot glue to make 6"-by-1" crystals (I'm using different dimensions for mine), but at least it's OTC. Seems to work well from my initial trials with LED's - the more glue is added on, the more diffused the light gets.

bfesser - 22-6-2013 at 08:11

I didn't know the source. I was just intrigued by your images, and decided to investigate. Dissecting the source URL lead nowhere, so I did a <a href="http://images.google.com/imghp?hl=en" target="_blank">Google 'search by image'</a>. Amazing what you can do on the internets nowadays... back when I started using them, it was all Star Trek and porn&hellip;and Star Trek porn.

[Edited on 6/22/13 by bfesser]

DubaiAmateurRocketry - 22-6-2013 at 09:24

I am recently using MDI to polymerize with some glycerin and ethylene glycol, I am worried that it says its carcinogenic. It barely have any vapor pressure, so i think breathing near it is okay, but my hand touched it few times, but i washed them so i guess I am perfectly fine right ?

bfesser - 22-6-2013 at 20:04

<strong>When will you people learn to define your acronyms before just dumping them upon us‽</strong>

I assume you're referring <em>ambiguously</em> to <a href="http://en.wikipedia.org/wiki/Methylene_diphenyl_diisocyanate" target="_blank">methylene diphenyl diisocyanate</a> <img src="../scipics/_wiki.png" /> (MDI).

[edited to remove inflammatory content]

[Edited on 7/9/13 by bfesser]

elementcollector1 - 22-6-2013 at 20:35

Thanks bfesser, I was kind of confused.
Quote: Originally posted by DubaiAmateurRocketry  
I am recently using MDI to polymerize with some glycerin and ethylene glycol, I am worried that it says its carcinogenic. It barely have any vapor pressure, so i think breathing near it is okay, but my hand touched it few times, but i washed them so i guess I am perfectly fine right ?

Copy-paste ninja strikes again!
Quote:
MDI is the least hazardous of the commonly available isocyanates but is not benign.[6] Its very low vapour pressure reduces its hazards during handling compared to the other major isocyanates (TDI, HDI). However, it, like the other isocyanates, is an allergen and sensitizer. Persons developing sensitivity to isocyanates may have dangerous systemic reactions to extremely small exposures, including respiratory failure. Handling MDI requires strict engineering controls and personal protective equipment.[7] Compared to other organic cyanates, MDI has a relatively low human toxicity. It is a potentially violently reactive material towards water and other nucleophiles.
- Wikipedia

Anyway, hot glue is still working out very well - now, to find a few pounds of the stuff and a wider nozzle for the glue gun.
Oh, and a few hundred more LED's.
If anyone's interested, I might post a few shots of the finished product - either in this thread, or a thread in Whimsy.

[Edited on 23-6-2013 by elementcollector1]

Variscite - 22-6-2013 at 20:36

Dubai, doing chemistry without gloves on even when working with hazardous substances? Thats not very smart. :(

elementcollector1 - 22-6-2013 at 21:06

Everyone starts somewhere... and some start safer than others.
Dubai, when you work with hazardous materials of any kind, it's usually a good idea to wear some gloves. I have heavy-duty yellow fake-leather gardening gloves, and they've stood me through most of the halogens, strong mineral acids, flames, and all manner of other nasty things.

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: removed unnecessary quoting]

[Edited on 7/8/13 by bfesser]

DubaiAmateurRocketry - 22-6-2013 at 22:34

Ok I will buy some thank you.

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: removed unnecessary quoting]

[Edited on 7/8/13 by bfesser]

unionised - 23-6-2013 at 01:26

Was the "MDI" a white crystalline solid or a yellow/ brown viscous liquid?

Also, buying just 1 pair of leather (or fake leather) gloves isn't a good solution to the problem of toxic chemicals.
Choosing suitable gloves isn't easy.
If you have a pair of gloves and spill stuff on them the stuff will, to some extent, soak into the material and diffuse through to your skin. The only way to avoid that is to throw the gloves away before the stuff diffuses through.
In many cases (and MDI is one of them) you would be better off with thin disposable gloves.

Fantasma4500 - 23-6-2013 at 07:42

you might wanna consider PVC as in bottles, the bottles made with PVC is usually somewhat thick and soft'ish
the thin bottles are usually PET, poly-ethylene-terapthalate (dont know i spelled it right this time :P)

ive melted PS on a steel plate on my hot plate and well its still sticking to the steel plate, what you need to do is melt it slowly, its very transparent also..

usually the melting point isnt a problem, i know with PS it surely wasnt.. just low heat, but the problem is if you can actually pour this stuff
ill tell you that when you have this thing molten, and some of it is still in there, you might just wanna throw it away because its impossible to get it off
or well i gave up on it, when small amounts were stuck to a steel plate

candle wax could possibly be done aswell but im not sure if it would be transparent enough

DubaiAmateurRocketry - 23-6-2013 at 07:43

Quote: Originally posted by unionised  
Was the "MDI" a white crystalline solid or a yellow/ brown viscous liquid?

Also, buying just 1 pair of leather (or fake leather) gloves isn't a good solution to the problem of toxic chemicals.
Choosing suitable gloves isn't easy.
If you have a pair of gloves and spill stuff on them the stuff will, to some extent, soak into the material and diffuse through to your skin. The only way to avoid that is to throw the gloves away before the stuff diffuses through.
In many cases (and MDI is one of them) you would be better off with thin disposable gloves.


It is a partial transparent liquid.
color is same as when sugar is half decompose and melted, brown, a bit viscous, and no smell.

bfesser - 23-6-2013 at 07:59

Quote: Originally posted by Antiswat  
PVC &hellip; the thin bottles are usually PET, poly-ethylene-terapthalate (dont know i spelled it right this time :P) &hellip; PS

You were close.
<a href="http://en.wikipedia.org/wiki/Polyethylene_terephthalate" target="_blank">polyethylene terep<strong>h</strong>thalate (PET)</a> <img src="../scipics/_wiki.png" />
<a href="http://en.wikipedia.org/wiki/Polyvinyl_chloride" target="_blank">polyvinyl chloride (PVC)</a> <img src="../scipics/_wiki.png" />
<a href="http://en.wikipedia.org/wiki/Polystyrene" target="_blank">polystyrene (PS)</a> <img src="../scipics/_wiki.png" />

[Edited on 7/9/13 by bfesser]

ElectroWin - 24-6-2013 at 08:22

re: hot-glue, i found that mixing in some paraffin also reduces its stickiness, making it more workable when warm.

and,
this article is about DIY plastic from starch:

http://www.instructables.com/id/Starch-Plastic-20-Pressure-C...

Intergalactic_Captain - 25-6-2013 at 05:37

On the hot glue note, think industrial...

http://www.bostik-us.com/markets/packaging/case-carton/therm...

If you can track down a case of this at a reasonable price, it might be an option - This is the hard, inflexible type of glue used in the cardboard packaging of just about everything you've ever come across. Our gluepots at work are set to 350degF for air-actuated glue jets, not sure what a working temperature for your application would be but it should be around the same - Key point is that it dries translucent, and relatively close to the amber color you're looking for.

Distilling Resin?

elementcollector1 - 26-11-2013 at 12:51

I would like to know if it is possible to distill the resin they sell at car repair stores in the interest of obtaining a clear product (which can then be used in the same way as the original). Granted, I should have bought clear casting resin, but I'm wondering if there's any way to fix my mistake.

Pyro - 26-11-2013 at 13:03

what's the main component? but I doubt it as it's probably a mix of many different things

elementcollector1 - 26-11-2013 at 13:10

According to the MSDS found here (http://apps.risd.edu/envirohealth_msds/Facilities/fiberglass...),
60-70% "Proprietary Resin"
30-40% styrene

The dictionary definition of proprietary really isn't helping with this one.
However, the styrene could distill off without too much trouble (BP 145 C).

Pyro - 26-11-2013 at 13:27

try it (maybe first in a test tube with a holed stopper and tube in case its a huge mess)

WGTR - 26-11-2013 at 13:52

Are you looking to mount element samples into a clear block? If so, you'll get better satisfaction
out of something that is intended for that purpose. Even some clear casting agents can yellow
as they age if their quality is not up to par.

A company that supplies these types of things is

www.smooth-on.com

Some people who do castings have recommended them to me, and I was happy with the
high-temp silicone rubber that I got from them. Anyway, YMMV (Your mileage may vary).

elementcollector1 - 26-11-2013 at 14:05

It's actually for a different purpose, but the product should be about the same - clear and transparent.
Can't find any pricing or online cart for that particular site, and it doesn't look like I have a local distributor... Darn. I guess I'll keep looking.

unionised - 26-11-2013 at 14:09

Buying styrene is probably easier than cleaning a distillation flask full of baked resin.

chemrox - 26-11-2013 at 21:06

As above I would guess that the glassware cost is much higher than the cost of new product. I have been cleaning a charred RB. I should have reserved it for crude distillations since I've now spent over the cost of a clean flask on ebay. Maybe even Ace Glass..

UnintentionalChaos - 27-11-2013 at 01:17

The "proprietary resin" is usually an unsaturated polyester. Addition of the catalyst crosslinks the polyester and adds in polystyrene chains. The properties of the finished product are dependent on both components. If you want a clear, colorless resin, I suggest a craft or hobby supply place. They sell similar products but with no fumed silica filler and with colorless resins (or additives) that resist light induced discoloration/damage. Typically, the catalyst added is also much less and results in a much longer, less exothermic cure process.

elementcollector1 - 27-11-2013 at 11:11

EDIT: I came across a simple, kid's recipe for modeling clay that involves equal parts Elmer's Glue-All, cornstarch and flour. What I'm wondering is - does this stuff dry translucent? I would like to either cast a 'brick' or 'shell' (depending on how thin it has to be to be translucent, if that applies) that will diffuse the light from 7-8 LED's to make an even color (the LED's are evenly spaced).

In addition, if I do have to cast a three-dimensional shape out of this, would it be possible to coat the sides with petroleum jelly for a 'mold release'? As far as I know, it should work - an often-used trick for glue bottles is to coat the bottle caps with mineral oil or Vaseline so they don't stick.


[Edited on 11-27-2013 by elementcollector1]

elementcollector1 - 1-12-2013 at 15:41

Ugh. I've had 3/4 of a bottle of Elmer's Glue-All inside the mold for 2 days now. There's an eighth-inch thick layer of dry glue on the top, but everything underneath is still liquid. The mold itself is composed of paper and wood. Is there any way to make this dry faster?
Perhaps dessicate it with something like H2SO4 in a separate container in a closed box?

halogen - 1-12-2013 at 16:15

Elmer's glue. Well I guess it makes sense, but thick layers Drying not polymerizing invites cracking too; maybe you'll consider letting it dry in layers, probably an oven or heat helps if it doesn't be comforted that that's what I'd try.

Also, if you have:
Clear detergent bottles
Milk jugues
The aluminum soda can plastic ring fish and aquatic life killing things, you know?
Whatever else is polyethylene or polypropylene (check the recycling number)
- That's basically wax and can be melted, cast, whatever very easily. If the colors are to your liking - you probably will have difficulty adhering inks or colorant to the surface. But one experiments. Don't melt PET, it chars.

Remind people, EVERYTHING is made of chemicals.

[Edited on 2-12-2013 by halogen]