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What to do with expanded polystyrene?

This topic contains 25 replies, has 20 voices, and was last updated by  Sylvia 2 years ago.

Peter pcofmind

What to do with expanded polystyrene?

23/05/2016 at 15:17

While most of the precious plastic types listed as process able are already recyclable in Sydney Australia by the local Council collections, and a good news is NSW will follow South Australia’s lead to give a nominal refund for plastic drink bottles from July this year to reduce the amount of litter, I have two problems that would be great for the Forum to suggest solutions on.

One of them is plastic shopping bags that come in a variety of materials and are not welcome in the recycle bins.

The second is that expanded polystyrene – the light, white plastic often used to protect equipment or furniture from shipping damage – is also not among the materials accepted for recycling either in the bins or in the recycling depos, because of its bulk.

Do you fellow plastic recyclers have an easy implementation for recycling these two types of “menace”?

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01/06/2016 at 02:04

There are these compactors to help decrease the size of the residue for industrials, it makes this sort of “poop”-looking extruded doe. It doesn’t look like the molecules have been compacted.
So idk if heat collapses the molecules.
Chemicals do… like acetone and diluente… but those release vapours, and making them doesn’t look so pretty either.

So, back to the heat: what kind of objects can we make with extruded “poopy”-looking doe (that hardens).

I’d say: boards and tubes. And while hot, wire?

25/08/2016 at 13:21

Acetone softens the polystyrene into a thick liquid.
You can pour into a mold or shape by hand.
As the acetone evaporates the material hardens.
As sourced from Google.

I used acetone when I worked with GRP, it did dry your skin out if you used it without rubber gloves.

15/09/2016 at 04:37

Hi all,

Very interesting subject around the expanded polystyrene. I’ve been doing some research and test regarding this subject, here are my latest conclusions.
potential uses:
1) expanded PS melts with diesel (makes napalm…), with acetone but also with Grapefruit essential oil (from the peels) which is an alternative used/patented by the company Polystyvert in French Canada. They are able to extract the raw PS for reuse, some horrid chemicals and the essential oil with can be partially re-used. Try to squeeze a grapefruit peel on a piece of expanded PS and touch with your finger 🙂
click here to see the corporate video
2)It can be re-used as insulating material (hot or cold) in lower income areas and easily assembled pieces with polyurethane foam to make walls/blocks. Downside: not fire-proof
Upside: very good insulator, can be “encapsulated” in between 2 walls in order to stay safe.
3) I’ve used a thicker mix of expanded PS with acetone base solvent to glue sticks/poles to rocks, it get’s really hard after a good week drying and last somewhat. You can also use strips of most fabrics dipped in the mix to be used the same way as plaster straps to assemble bigger structures, with fabric it really get hard to separate/tear when dry. You can also waterproof porous surface with this thin coat of “varnish type” of mix, nothing ecofriendly but it works and it’s cheap – cement roof and wall, rusted metal surfaces, terracota….
Downside: bloody messy, stinky all over your hands/place. You get quickly stoned using this, even outside (please avoid, very bad for health).
4) mix acetone + expanded PS with cement = total failure, could be tested differently. My cement reacted strangely and didnt dry became very brittle.
5) ground up expanded PS can be used in concrete mixtures directly, I’ll get a picture as soon as I can, ratio is quite high and material seems solid enough.
I would personally go for solution number 2 for countries which regulations are less… anal.

Picture of small stick stuck to a bare rock. The biggest issue is to get all the bubbles out of the mixture before it dries out. I observed that when you let it set in a close glass jar the bubble go away in the end.

20/09/2017 at 11:59

I believe there are collection containers outside a lot of Coles and Woolworths for plastic shopping bag recycling.

Alternatively, you can imitate Terracycle, who stacks a few of them flat on top of each other, maybe 6-12 at a time, and then uses a hot iron to fuse them together. The resulting thicker plastic can be used to handcraft purses, pencil cases, backpacks and items of the sort.

Polysterene containers make excellent vegetable planters. Polysterene is said to be stable enough so you dont have to worry about chemicals leaching into the soil. If instead of at the bottom of the container, you cut draineage holes on the sides, 1-2 inches from the bottom, they store a healthy amount of moisture, similarly to “self watering systems.” I’ve been growing tons of veggies out of them for a few years now and they’ve survive on sydney rainwater only.

you can also fashion a traditional self watering planter as shown in the photo but i think the holes on the sides work perfectly and are no work at all.

29/10/2017 at 06:57

It makes a nice glue.

Regarding the grapefruit oil comment. That is limonene. a common industrial chemical and used to dissolve printed styrene supports for 3d printing.

Acetone, napatha or gasoline all make a good solvent to melt expanded foam.

More research is needed to see ways to make it into a boat building resin, or wood glue.

It is not UV resistant, so it will need the addition of something like carbon black to prevent it from rotting in the sun.

Sunlight kills styrene very fast. Usually 2-3 years will totally deteriorate a piece of uncovered styrene board in the sun as the UV light breaks it down.

It can also be gasified and burned rather cleanly, as It produces almost no smell in my gasifier stoves Same as the polyethlyenes. ABS and PVC however are not very good gasifier fuels as they release a toxic gas because of the chlorine atoms in the formula.

29/10/2017 at 12:22

I’m currently feeding expanded polystyrene to mealworms in a small glass fishtank, apparently the by-product is usable in the garden. Although I would want to see some test results to confirm I am not adding plastic to my food supply directly! Possibly getting enough via seafood at the moment.
The mealworms are quite slow processing the PS so a larger number of them may be needed.

29/10/2017 at 23:07

Can’t you just undo the expansion by heating it up? In school we built an ofen out of styrofoam once and the hot air destroyed the styrofoam roof by shrinking a hole into it…
Please correct me if I’m wrong! 🙂

Thanks & all the best

14/02/2018 at 14:10

Hi everyone,
Has anyone tried feeding expanded polystyrene into one of Dave’s machines? Seems to me that as its 95% air it wouldn’t be a great idea… I wonder if the polystyrene he has tested is solid polystyrene (plastic cutlery etc.). I am testing the acetone-PS mix now – if just left to harden naturally it takes a few days and has bubbles still (I think formed by acetone evaporating). I will also be testing a few different ways of drying it to see if I can improve this. Has anyone then tried putting this dried/reduced polystyrene into Dave’s machines?

15/02/2018 at 07:42

Hi everyone, I’ve been recycling Styrofoam for about 5 years…I melt it with acetone and trepens, and shape it in to pots as you can see in the image.
You can check out my facebook page, there are few more pics of what I’ve done. among waste reduction and Conscious consumption tips. Tell me what you think. Regards!!


15/02/2018 at 07:48

By the way, this is a handmade domestic procedure…globes mask & safety glasses included of course 😉

16/02/2018 at 05:50

Good day. We are currently studying about making a roof tile from waste expanded polystyrene by melting and mixing it with sand. If you guys know the ASTM standard for composite plastic pls let me know. Thank you.😊😊😊

05/03/2018 at 15:20

@btmetz, would a mixture of polystyrene and sand in the shape of a roof tile,a paving stone or a building block, be more UV-resistant ? If not, is it just the outer layer of the product or even the inner layer can be affected ?

Your answer might suggest to adopt or avoid the use of EPS for such applications.

08/03/2018 at 06:00

good idea!, show us the results please

28/03/2018 at 19:52

Hey guys, so i’ve started sorting out my different plastics and in the PS zone I have quite a few expanded PS (mainly ice containers).
One of the guys i work w/ is a senegalese wood worker and already back then before coming to france, he would make glue that way.

Just in order to gather maximum different intell on the subject; what kind of dosage would you recommend for optimal glue (ratio kg os PSE/ liters of “diluant”)

Also, following someone here’s advice (so sorry can’t find the message again), i covered the pot where i mixed PSE & diluant with a plastic film, hopefully getting rid of air bubbles w/ this process.
Is there anything special to be aware of if willing to sell small quantités to craftsmen around my business?


05/04/2018 at 13:31

With regards to dissolving PS foam to make a moulding compound, or glue, you may be interested in this video.

Cuba’s DIY Inventions from 30 Years of Isolation

The typical solvent used was gasoline. Not nice to work with, but it got the job done.

09/04/2018 at 05:27

I’ve use polystyrene with electronics. It’s pretty resistant to electricity so I’ve used it to repair laptop charger cords. They always seem to break at the place they go into the device for me. In order to fix this I cut them off and stick them into a jar with some acetone in it. The acetone is absorbed into the PVC insulation. After a while I take them out of the jar and peal of the PVC by hand. Next I fix the problems with a soldering iron, test the results and then encapsulate the whole thing in polystyrene. I put it some place cool to dry of and harden for a few weeks. It’s best to keep it out of the heat as that will cause the polystyrene to expand which is undesirable in this instance. The method has proven vary effective, but you need to be careful that there are no flaws when you do it because if it breaks again getting the polystyrene off is harder then with the PVC.

This is the best used I’ve found for it yet although I keep some liquefied polystyrene in a jar to use for various things from time to time (the jar keep the acetone from drying out). I’m guessing it could be used for other electric things like maybe you could use it to encase some simple circuits avoiding the need for a circuit board. Of course if it breaks fixing it would be a pain.

10/04/2018 at 13:57

Hi Guys Polystyrene can be turned into aerated concrete, beanbag filling, packaging filler etc
1 aerated concrete the polystyrene is broken down by a machine like a shredder but has comb like metal teeth which breaks the polystyrene into balls. Essentially it rips it apart into tiny ball like bits, the balls are then mixed with concrete and used mainly in the landscape industry for build ing non structural walls. In australia it is called a hebel block. (Private message me if you want the recipe). Also this can be used for other applications like tables or chairs or whatever you can thinkof quite a versatile material.
2 Beanbag filling – this is the same machine doing the work but the polystyrene balls is collected and bagged up and sold to be used as filling for beanbags.
3 Packaging filler – same as above but used for a different purpose.

10/04/2018 at 14:08

@btmetz Could we use a uv lamp to breakdown quicker? I think an experiment would be needed and I will start this week and give results.

06/05/2018 at 02:37

Hi Guys I was sent a private message for a recipe of the aerated concrete so I thought it would be good for all to see and share so here is the link.


14/05/2018 at 00:01

How about chipping the expanded polystyrene into small chunks, and then using it as insulation around biogas digester tanks?

In warm countries, biogas digesters can be built with little in the way of insulation. But in colder climates it is more difficult to keep the anaerobic fermentation active – as the bacteria cannot function below particular temperatures.  Hence the fermentation tanks need to be well insulated.  Even if buried, heat loss to the surrounding ground could be considerable – and so a thick layer of insulation would be an advantage.

There are probably plenty of non-plastic materials that can be used for insulation, such as glass fibre, wool, or straw.  But waste expanded polystyrene could have some advantages:
– it is cheap
– it still insulates if it gets wet
– it doesn’t rot

Also, the flamability of expanded polystyrene will be less of a problem if it is packed around a tank full of bubbling slurry, than if used for residential insulation.

(edit: Hmmm. That’s got me thinking about the possibility of moulding components for biogas digesters using HDPE or PP….)

08/06/2018 at 18:34

EPS has extraordinary properties such as density, longevity, flex recovery, and water resistance.  I founded Enstyro Inc. which invents equipment and develops uses for this material.  In the decade we have been in business, we have found many great uses for EPS and shipped EPS recycling equipment around the world.  A customer in the Maldives that makes building blocks from EPS concrete introduced me to Precious Plastics.  There is great value in the low density, but these extreme properties mean that you need to get the particle size right for the job.  This video describes how Enstyro equipment creates the right EPS particle for each specific use.  https://www.youtube.com/watch?v=oDvQpqsVBno&t=56s

With the perfect EPS particle the possibilities are endless.  We recently sent our third shredder to a single company in Australia that makes a stucco or render as they call it down under.  A customer in Nigeria is making a sound proofing decorative veneer out of light concrete.  A Texas company is using our equipment to produce pump-able concrete firewalls.  Mixing EPS in concrete gets rid of the flammability issue.  A New York City organization is using Enstyro equipment to produce aggregate for green roofing soil which helps insulate the building while consuming CO2 and reducing run off during storms in the concrete jungle.  A university in Canada is mixing Enstyro Shred with natural materials like clay to design new building materials for the developing world.

There are so many uses and our favorite is concrete because we replace mined aggregates while adding insulation and crack resistance.  A little EPS in concrete maintains the high strength while preventing thermal cracking thus making concrete more durable.  Floating concrete is simple when you have the right mix of aggregate sizes like in normal concrete, but with a near weightless, moisture resistant aggregate.  Replacing about half the aggregate in concrete can produce a tough, structural concrete with much increased insulating value.  This added insulation can stop the condensation on concrete and prevent moldy basements in many parts of the world.

I do believe that the next material age is at hand and it will start despite the corporate oligarchs, not because of them.  There are many new materials and some new equipment yet to be introduced by Enstyro and our inventive and insightful customers.  We are here to help if your ready to recycle EPS into a better tomorrow.  http://www.enstyro.com

18/06/2018 at 16:28

Hello People,

My personal experience was, shredding the Styrofoam leads – surprisingly – to a reduction of the volume of the styrofoam.

From a 90 liters bag,  I got 5 liters of shredder styrofoam.
These volumes are only an estimation, but next time I try I’ll make some pictures.

Next step is to try in the Injection machine, I’ll try and tell you later.

10/07/2018 at 18:00

Most grinders will crush the eps in the process.  Enstyro equipment was designed to shred foam without crushing.  Typical packing foam has a lot of empty space and our equipment still only reduces the volume by half.  A bag of enstyro shred is around one pound per cubic foot.  That depends on the incoming EPS of course.  Check the density of your shredded foam if you want to know how much crushing is going on in your grinding method.

Contact [email protected] if you want to produce the best EPS aggregate on the planet.

20/06/2019 at 15:52

Hi Dave, @enstyr
Am I correct to asume your machine is closer to a blenders than a shredder?
You are on an Open Source forum, so I hope you don’t mind me asking about your ‘trade secrets’ 😉

22/12/2019 at 03:33

Hi – I tried making glue out of styrene and acetone. Youtube videos show the styrene melting invisibly into the acetone and creating a glue. My styrene becomes an elastic lump like playdough and never looks like dissolving. Anyone got any suggestions please?

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