Introduction: Make Your Own Plastic

Many of us use plastic in our projects, but did you know you can melt down and reuse much of the plastic found in your house? In this instructable you'll see how to recycle plastic to be reused for whatever you want.

Step 1: What Type of Plastic Can Be Reused?

For this method we will be reusing high density polyethylene (HDPE) plastic. You can identify this plastic by the recycling symbol on the bottom of most plastic containers. HDPE will be identified by a small "2" in the center of the recycling symbol, and will sometimes even be accompanied by "HDPE" written next to the symbol.

When compared to ABS plastic:

HDPE:

  • density - .958g/cc
  • tensile yield strength - 20.6MPa
  • melting point - 129 C

ABS:

  • density - 1.05g/cc
  • tensile yield strength - 41.5MPa
  • melting point - 220 C

While HDPE is not as strong as more widely used polymers such as ABS, it is good for low stress applications such as project enclosures, lightweight mounting solutions, and more. And the best part, it's free!

Step 2: Materials and Tools

To start this project you'll need:

Materials:

  • HDPE plastic in the form of containers and/or plastic bags
  • Baking pan
  • Wax Paper
  • Non stick cooking spray

Tools:

  • Scissors
  • Oven or toaster oven
  • Gloves (preferably welding gloves or similar heat resistant gloves)

Step 3: Preparations

If you decide to use plastic containers such as milk jugs you'll need to cut up the plastic into smaller pieces. Using your scissors cut the plastic into nickel sized pieces. If you use plastic bags it helps to tie them in a knot. Plastic bags tend to shrink in peculiar ways when they melt, knotting them makes them easier to work with. Once you've cut up your plastic into small pieces preheat your oven or toaster oven to 350 degrees Fahrenheit. Make sure you do this in a well ventilated area! While the plastic shouldn't release an excess of fumes if done at the correct temperature, any fumes it does release will be nasty and should be avoided.

Next you'll want to grab what ever you decide to use to melt your plastic in. An old cooking sheet or pan can be used. Line the pan with a sheet of wax paper and spray a light coat of non stick spray or similar lubricant across the sheet.

Another option, if you've built the furnace shown in my last instructable, you can cast aluminum molds for melting down your plastic.

Step 4: Time to Melt!

Place your plastic into your pan or mold and place in the oven. Cooking should take between 30 minutes and an hour depending on your oven. Keep an eye open for signs of burning and adjust the heat as necessary. The plastic will go soft and malleable as it melts. Once all of the plastic is melted you'll want to grab your pan or mold out of the oven (make sure you have your gloves on!) and check for gaps and voids in the plastic. If you want cleaner edges on your plastic, fold the edges of the plastic over on itself. Once you're happy with your plastic, throw it back in the oven for another 10-20 minutes to melt down and make the part solid.

Once your plastic is done you'll need a way to keep pressure on top of the plastic while it cools. Otherwise the plastic will try to buckle and warp as it cools. This can be done with a couple of pieces of wood and either a couple of clamps or a heavy weight.

Step 5: Make Something!

Once your plastic is cooled it can be used for whatever you can think of! You can trim it and make plastic stock for later use, or cut and machine it into anything you come up with. I've found that a small jig saw works well for cutting and 80-180 grit sand paper for shaping.

Go and use your plastic for your next project and thanks for checking out my instructable!

Comments

author
carol.franks.927 (author)2016-12-04

I like the idea of melting plastic. I've been thinking about making blocks with melted plastic and building a shed with it. I crochet with plastic bags, I cut them into strips, across the bag, I link the strips together, roll it into a ball and crochet. I make rugs and bags.

author
TheAZAndyman (author)2016-07-07

I wonder if I chip/shred/cut it up and put it in a metal tray in a solar oven and leave it for the day while I went to work if it would it melt down into the pan and leave a flat sheet of plastic. Might have to build a solar oven and cut up the milk jugs to find out. Anyone try something like this.

author
posteljooni (author)2015-04-14

It looks like a great loss of energy, when used just for the sake of recycling plastic.

But could be done in winter, though:
while melting the plastic, you will heat up the house too!

author

How do you think plastic is normally recycled?

author

Even if it is recycled this way (though i doubt they use kitchen ovens and melt 1-2 kg of plastic), the economics of scale would make industrial recycling more effective and less wasteful.

All this topic stresses the issues of pervasiveness plastics and it's recycling... Too many problems off the plastics.

author
lukemarq (author)posteljooni2015-04-24

Shouldnt do it inside.

author
posteljooni (author)lukemarq2015-04-25

Yup, good point, as the fumes are not good for your health, most probably. In that case, I would think of other possible recycling methods - this one based on melting is a huge waste of energy, I think...

Anyway, biodegradable PLA is the future for the plastic bags, I hope. At the moment it is better to avoid plastic bags in the first place (e.g., switch to cotton bags, which are more durable and sustainable).

PS: this is not to criticize the author! Just "my 5 cents")

author
ithica2012 (author)posteljooni2016-05-22

It is less wasteful then tossing in the trash but I think this would make a good source of machinable plastic for prototyping parts and it will be cheaper then buying new plastic. If you have a use for the stuff this is a good idea and no more wasteful then baking a potato.

author

"Two cents"...No criticism...Just getting mine in, as well. :-)

author

Lol, thanks) /
It's been a literal translation from http://translate.academic.ru/мои+пять+копеек/ru/en/1

Lesson learned, I guess, thanks)

author
holymoses (author)posteljooni2015-07-22

A good point!

:-)

author
matt_the_man (author)2016-05-29

there is a site on the net that has all the blue prints for making anything out of recycled plastic.including the machines from shredders to extruders. check out precious plastic.com

author
IzakT (author)2016-05-24

Cool, I am busy getting the parts together to build the shredder. Also very tempted to buy the DIY kit from Filastruder

author
dan3008 (author)2016-05-22

Ah, Now I'll I need is a fillement extruder :D

author
IzakT (author)dan30082016-05-24

Hi dan3008,
Check out Preciousplastic.com. They have open source plans for a shredder, extruder, injection mold machine and compression machine.

author
dan3008 (author)IzakT2016-05-24

I've got a copy of tgeir plans saved on my desktop :)
Its only time and finances stopping me already having one :)

author
funny1048 (author)2015-10-06

can i melt it in boiling water by adding salt to the water to raise its boiling point

author
oky jim (author)funny10482016-05-22

No. The so-called melt temperature of hdpe is about 350 degrees F. The boilding point of salt water is only a few degrees higher than unsalted which is 212 deg. F.

author
SherylinRM (author)2016-05-22

I have a broken plastic gear I need to replace. It costs $45 just to have the company look at it to decide "yep it is a broken gear". Before they will send me one. Of course I have topay for shipping each way as well.

Ok so this gives me an idea for replacing said gear.

Thanks for this :) Two thumbs up :)

author
jessie49 (author)2016-05-22

hmmmm, I carve things out of wood, dolls, animals etc I have seen the "ivory like" plastic that is sold on eBay to carve I wonder if this would work? Also could be made into dollhouse furniture maybe sounds like great uses for me thanks!!!

author
camscam (author)2016-05-22

To be a bit pedantic, you're not making plastic....

It's already plastic.

author
ithica2012 (author)2016-05-22

I saw a post where you can make machinable wax you take paraffin wax and melt it then add plastic bags then pour it in a mold.

author
mdeblasi1 (author)2015-04-14

Ok wait a minute.
If grocery store bags are #2 HDPE, why won't the recycling center take them?

author
fred_ (author)mdeblasi12015-04-14

A few reasons. The recycling number doesn't mean it gets recycled it just says what it's made of. That's important since you don't want mixed plastics and aids the recycling center people sorting stuff on a conveyor. They can't spend the time ($) examining every pc of plastic moving down the conveyor under a microscope. Mixed plastics don't have a lot of uses the same way mixed ground up steel and aluminum cans doesn't have a lot of value.

2nd there has to be a market for the particular type of plastic on the conveyor. PET soda bottles are easy to identify on the line relatively clean without looking at the tiny numbers and get a relatively unmixed bales of plastic for further processing. There is a buyer for that.

3rd plastic bags don't behave on a conveyor line they blow around get caught in mechanisms and gum up the works. They fill with air and take up a lot of space and don't weigh much. Thin film larger area low density... bad return on labor. Not all bags are made of the same stuff and many plastic films are actually many layers of different stuff. So you can't say put all plastic bags in this chute.

4th. since they're thin they don't grind up into approximately grain of rice size chunks to be useful in plastic processing equipment. Extra post processing $.

So it's makes sense to say don't put #2 bags in the recycle bucket since we have to pay someone to take them back out and put them in the land fill anyway. Which isn't to say paper bags are a better environmental deal.

author
FlorinJ (author)fred_2016-05-22

I think paper bags are a way better environmental deal. They require less energy for being manufactured and are fully recyclable. Even if landing in landfill, they degrade quickly and without releasing unnatural chemicals. You can even compost them. Much of the paper (not even half, but still a significant amount) produced in developed countries is made from cultivated wood, which is a renewable resource, unlike oil. None of these applies to plastic bags.

author
RonGarza (author)fred_2016-05-22

Necessity is the mother of invention re: "So it's makes sense to say don't put #2 bags in the recycle bucket since we have to pay someone to take them back out". Someone? or something?

.

author
lukemarq (author)fred_2015-04-24

From the info you've given about plastic bags paper sounds pretty good in comparison. Paper can be recycled into lots of things and bio-degrades. Depending on how the paper pulp is obtained it can be sustainable. More-over, not many things makes a city look more trashy than plastic bags caught in the trees.

author
The Rambler (author)mdeblasi12015-04-14

I have asked myself this exact same question. Recycling centers (at least American ones) are bizarrely specific.

author
CraigL20 (author)The Rambler2016-05-22

Compared to what?

author
mcysr (author)The Rambler2015-04-14

You ought to see what they require in Japan.

author
The Rambler (author)mcysr2015-04-15

Haha, I don't think I want to.

author
mattcintosh (author)The Rambler2015-04-14

Stuff like that gets caught in the equipment

author
The Rambler (author)mattcintosh2015-04-14

Huh, you know I never thought about the sorting equipment. I guess that's why they do have plastic bag recycling containers at grocery stores. Since there's no sorting they can probably just dump all of it in and melt it down.

author
scook9 (author)mdeblasi12015-04-14

They generally will, you just have to bag them up (stuff a bunch of them into one bag).

author
BrianM172 (author)2016-05-22

Does PAM work for the non stick spray?

author
gromitnyc (author)2016-02-28

Try parchment paper instead of waxed paper. You don't need the cooking spray and the plastic comes off nice and clean.

author
posteljooni (author)2016-01-02

RE: "you clearly do not think", "Use your brain more and your mouth less."

- Kid, this is not a site for you and for soothing your anxiety and strange aggression. Solve your problems elsewhere, please!

instructables - Be nice.JPG
author
WilliamM109 (author)2015-12-01

Cool

author
kidintheworkshop (author)2015-10-10

like your sheet material i made a structtable on making block matreal

author
davehartles69 (author)2015-05-02

great instructions I will be trying this soon

author
mvillalpando (author)2015-04-22

I've used a heat gun in the past to melt certain plastics. I've used many types of plastics (re-purposed) in order to do Plastic Welding and repair other plastic pieces, or create molds as well. Good Instructable!

author
lukemarq (author)mvillalpando2015-04-24

Great idea, so mold them into sticks for use in glue gun? Will make some bad fumes when used in a gun but if you prepare for that it is a great idea.

author
fred_ (author)lukemarq2015-04-26

Typically you'd extrude push it thru a round hole and pull on what comes out to make a long pc. PP and PE don't really stick to anything so it wouldn't work like a glue stick. You can use a thin stick of this kind of plastic with a small diameter heat gun and weld similar PP or PE pcs of plastic together with it. Glue doesn't work very well on PP or PE.

Most plastics don't requiring anything other than normal industrial building ventilation when molding with it. More air turns than a house though. Some like PVC are an issue particularly if you overheat it for a period of time.

Plastic bags get a bad rap mostly because people don't dispose of them properly and they end up blowing around. Or you're friendly waste disposal company takes it on a barge and dumps it in the ocean. Energy wise, sanitary wise, water consumption wise they aren't worse than paper bags. It probably makes for sense to make something useful like a plastic bags rather than burning off the propylene and ethylene gas when you're processing oil and natural gas.

author
yomero (author)2015-04-20

Could this be done on PET bottles?

author
push_reset (author)2015-04-16

This is really useful, and gives creatives a way to reuse many items that would end up in the pit too soon. It's simple enough to do consistently if plastic is needed in your designs and a great way to plant the reuse and waste conscious seed. Love it! I see a lot of safety concerns, which is def valid. I will be and I advise that peeps do their own research on the safety of melting thermoplastic types. It's always a good idea to educate yourself when you have unanswered questions about safety. I've already learned a lot from the comments below! Tx for posting!

author
shannonlove (author)2015-04-14

There is no reason to use dedicated equipment when working with thermoplastics. These are all food and medical safe plastics, the kind our food, medicine and drinking water touch and flow through every day. We use them for these purposes precisely because they can be heated and shaped without producing any risky byproducts.

Thermoplastics are like a dough which at room temperature is frozen but when warmed becomes malleable. Just as freezing and warming dough to knead it does not alter its base molecular structure warming the thermoplastics does not alter them either. They are just as food safe when warm and malleable as when cool and froze.

Out gasses are not particulates, they are gasses of very light molecular weight that dissipate. They do not contaminate equipment even when the gasses are dangerous which in thermoplastics they are not. The outgassing that does occur is trivial and harmless. Usually you can't even smell anything when shaping thermoplastics. The gasses that do escape are either inert or harmless e.g. microscopic amounts of propane and other short chain hydrocarbons that don't contain covalent chlorine. They are only in the plastic from being physically trapped in microscopic pockets during manufacturing like the nitrogen inside styrofoam. They aren't actually part of the plastic. Since plastic from finished products has already been heated and molded, usually several times during the production process very little trapped gasses remain in any case.

Even if you did completely liquify the themoplastic and a drop got on the equipment it would cool back to its inert and easily wiped off form and 2) even if you did somehow manage to eat it, it would pass the the digestive system harmlessly.

You'd have to actually start a fire and change their molecular structure in particulates from thermoplastics. But then burning anything produces dangerous by-products.

If everything is dangerous, nothing is dangerous. Understanding real, absolute risk is critical to being really safe and more important, doesn't cripple you from fear.

author
Andsetinn (author)shannonlove2015-04-14

Absolutely correct Shannonlove.

Burning plastic (I'm not talking about throwing it on a open fire) is actually the most environmentally friendly way to "recycle" it. If you add plastic to trash that is to be burned (in special trash burning machines) you will increase the temperature of the flame and by doing that get cleaner burn and less pollutants from the fire.

author
ksexton1 (author)Andsetinn2015-04-14

The most environmentally thing to do isn't burn it, but to actually recycle it. Burning it, or other trash without generating lots of nasty pollutants, requires other fuel, like natural gas, generally in an afterburner setup, where the gasses from the incinerator are passed through a high temperature gas flame. Burning any trash is a bad idea, if you accept that carbon dioxide we add to the environment isn't instantly absorbed by nearby plants, we'd probably be better off burying all trash that isn't going to leach toxins into the groundwater. But that would still not make a dent in the amounts of carbon we are digging up and burning in the form of oil and coal.

author
Andsetinn (author)ksexton12015-04-15

First, plastic is made from oil. Plastic need to be of high purity to be usable and used plastic is simply not clean enough to be practically recyclable. It is more economical and "cleaner" to make new plastic from oil and burn the dirty plastic instead of oil used to create the new plastic. Burning plastic with other trash in the correct equipment will reduce the "nasty pollutants" from the trash and you are actually saving the natural gas you would otherwise use to reduce pollution. Burning trash is very good way to get rid of trash and the burn creates heat that can be used to heat houses or create electricity. Since USA uses coals and natural gas for about 65% of electricity production (20% nuclear power) burning trash and using plastic to reduce pollution will help save the environment. Interesting side note is that if you drive Tesla or other electric car in USA, it is 65% non-renewable energy and 20% nuclear powered :). Burying trash uses lot of fuel (think of all the big trucks and diggers) and wastes land that could otherwise be used for living or farming. Feel free to disagree but please do some research on your own. I worked for over a decade in the plastic industry and went to quite a few seminars were specialists discussed plastic and the environment.

author
ksexton1 (author)Andsetinn2015-04-15

Most burning of trash is not done to produce heat, but just to get rid of it. Many plastics can easily be recycled, producing plastic that would otherwise be made from oil, at a lower cost, but if the type of plastics are mixed, or contaminated, the results will be low grade material that is not in demand. It still can be used for making trash cans and benches, but not items similar to what it started as.

Burying trash and burning it for heat both take the same big trucks to haul, so you can't use that just in the balance on the bury side. Many landfills are on otherwise useless land, if you equate all land with all other land, the vast majority of the US is empty unused land.

For burning, it still has to be collected, hauled, sorted, etc. Burning of certain plastics will produce gasses that are not only harmful to people, but highly corrosive to the equipment, if it's designed just for the less harmful types. If you are burning general trash, you are going to have a waste product at the end that still has to be disposed of, because there is a certain percentage in it that is not burnable.

I've never really seen anyone seriously advocating burning otherwise recyclable plastic before. Food and beverage containers will still be made from virgin plastic made from oil, partly because that has been made into law, but those used containers are just fine for putting into other products.

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