Instructables
**Note: If you like this Instructable and are looking for something a little more challenging that will yield better results then check out my new potato plastic instructables here http://www.instructables.com/id/Starch_Plastic_20_Pressure_Cooker_Hacking/**

Also if you have questions and want some expert answers try heading to this website http://green-plastics.net and just post your question on the Q&A board, they will be able to help out with your question in a more timely manner! 

Have you ever wondered if there is a more environmentally friendly way to make plastic with OUT using foreign oil? Currently, it is estimated that the worldwide production of petroleum based plastic is around 100 million tons annually, and that seven million barrels of petroleum are required PER DAY to produce that plastic ( info source ). What if we could take that number and cut it down to zero! This is all possible with the eco-friendly plastic of the future, and you can make some right now- OUT OF A POTATO! When I first discovered that you could do this, I used corn starch, water, and corn oil to make the plastic; I then made a science fair project out of it, won second place at my school, and won honorable mention (3-6 place) at the 2003 Regional Science Fair. The plastic I made for the science fair worked, but it dried out and became brittle in about a week. A few years later, I discovered an article describing a way to enhance it's plasticity by altering the chemical composition of the starch.
For this instructable, I will describe how to make plastic from scratch, by extracting starch from a potato, and processing it into a resin with household items. If you don't feel like taking the time to extract the starch from a potato, you can just use corn starch instead. This is a project for all you environmentalists, tree hungers, global warming believers (I am not one by the way), and especially you Al Gore.

Lets have some fun and make potato plastic!

 
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Step 1: Gather Materials

Picture of Gather Materials
Most of the materials you will need will be in your house or can be bought at most supermarkets and home improvement stores.

Ingredients:
2 White skinned potatoes OR potato starch OR corn starch
water
100% Vegetable Liquid Glycerin
White Vinegar
Food Coloring

Tools / Supplies:
Non stick pan
Spatula or Spoonula
Stove Top or Hot Plate
Knife or guillotine

Optional:
blender
peeler
filter
casting compound

Step 2: Optional: Extract the Starch!

Now that you have a potato, you might be wondering just how we will be making plastic out of this? The answer: extract the starch. How will we do this? BLENDER! Since potatoes are about 95% starch (besides the water), making a potato into a powdered starch form, is relatively easy.
A note to younger viewers: be sure to ask your parents if it is alright to use a peeler, knife and blender, and always use caution when working with exposed blades.
1) Get a potato, and wash it.
2) Use a peeler to take all the skin off.
3) Cut the naked potato up into cubes your blender can handle.
4) Add about 1 cup of water and the cubes to the blender, and turn it on high for a minute or two.
5) Use a coffee filter to strain off the cloudy water.
6) If you plan on making the plastic right away, drying the mixture is not completely necessary, but if you plan on storing it for a while, spread it out on wax paper in a sunny area for it to dry (it could get moldy otherwise).

Heres a suggestion by legionlabs to purify the starch extracted from the potato, by removing unwanted cellulose:
"Given only potatoes, you might be able to increase the purity of the starch for your process by removing cellulose using this reagent, which can be made from commonly available materials:

http://en.wikipedia.org/wiki/Tetraaminecopper_hydroxide

You can reuse the reagent by precipitating the cellulose out by acidifying the mixture, filtering out the cellulose, and making the reagent basic again."

If you do not wish to make the starch from scratch, you can order pre-made higher quality starch online, or buy it at your local grocery store. Corn starch and tapioca starch also work well to make plastic with. On to step 3...

Step 3: Mix it Up !

Now that you have gathered all the necessary materials and ingredients, its time to mix up a batch of potato plastic. A note to younger viewers: be sure to have a parent with you when using the stove, I don't want you to burn down your house because of this instructable! Also, beware of the starch plastic resin when you are pouring it into a mold, it is very hot and will burn you if it gets on your skin, you can never be too cautious with boiling hot substances.

1) Measure out 60 ml (4 tablespoons) of cold water and pour it into the beaker or container your heating the mixture in.
2) Measure out 10 grams (or about 1 tablespoon) of starch ( the potato / corn starch you made or bought) and add that to the water.
3) Add 5 ml or about 1 teaspoon of acid (vinegar) to the mixture.
4) Add 5 ml or about 1 teaspoon of glycerin to the mixture, more glycerin will make it softer and more flexible, less will make it harder and stiffer but more brittle.
5) If a colored plastic is desired, add in the food coloring now. About 5 drops is good enough.
6) Turn the burner on low and constantly stir the mixture. When it starts to thicken up turn the heat up to medium and stir even more. When it starts to boil, keep boiling it for 5 minutes. You want it to be very clear and sticky (not like toothpaste though, think flubber)
7) You should now have a "gooey" substance that you can pour into a mold, or you can pour it onto a sheet of aluminum foil/silicone heat pad to dry.
8) Depending on humidity, it should take about 1 day to dry in a sunny place. You can dry it faster by putting it in an oven set to 150 F for 1-2 hours.


Step 4: Use it !

So by now you should have a glob of messy starch plastic resin that is ready to be molded, injected, shaped, and formed into anything you want. A major advantage to this plastic, besides the fact that it does not use petroleum, is that it is also 100% biodegradable! That means in the right conditions, it will decompose in months instead of thousands of years. Its time to get creative and figure out things we can use it for.
Possibilities include:
-Plates and dinnerware
-Plastic bags
-Cups
-Bowls
-Pens
-And whatever else you can imagine...

a video showing a piece of colored plastic that is very flexible and strong (the tear in it is from drying)

Step 5: The Science behind it.

Now that you have made green plastic to your hearts content, you might be wondering just HOW its possible to make plastic from a potato? To find out we must look into what starch is made out of at a molecular level, and how plastics are formed. I will use some help from our good friend Wikipedia to define some of the terms we will be talking about.

First, lets look at how regular petroleum based plastics are formed. According to Wikipedia plastics are:
polymers: long chains of atoms bonded to one another. Common thermoplastics range from 20,000 to 500,000 in molecular weight, while thermosets are assumed to have infinite molecular weight. These chains are made up of many repeating molecular units, known as "repeat units", derived from "monomers"; each polymer chain will have several 1000's of repeat units. The vast majority of plastics are composed of polymers of carbon and hydrogen alone or with oxygen, nitrogen, chlorine or sulfur in the backbone. The backbone is that part of the chain on the main "path" linking a large number of repeat units together.

If you want a really good visual explanation of polymers go here to polymer planet.

So now that we understand polymers and how regular plastics are formed, lets look at how this happens with starch.

Starch is mixture of two polymers called Amylose and Amylopectin, in a ratio of about 1:4 ( 4 being the Amylopectin). Amylose is a linear polymer of glucose linked with mainly a(1 --> 4) bonds. It can be made of several thousands of glucose units , where as Amylopectin is a highly branched polymer of glucose.

What does all this mean? Well to get something that resembles plastic, we need to have LONG STRAIGHT chains of polymers. Since starch has both straight and branched polymers, we need to remove or alter the amylopectin, so we are left with long straight chains. Since going through and picking out all the individual amylopectin molecules with an electron microscope is not an option, we had to alter the starch. We used vinegar (acetic acid) to break down the amylopectin into straight but short molecules of dextrin ( commercially dextrin is produced from amylopectin by Hydrochloric acid hydrolysis: the amylopectin is roasted in vessels jacketed in hot oil - the oil is heated to 450C - at the same time HCl is added to the amylopectin - the acid plus the heat causes the molecular structure of the starch to change/polymerize ).

So now we are left with amylose and dextrin to which we added glycerin. Why did we do this? Well, not all normal plastics are soft and flexible. To achieve this property something called a plasticiser is added to the plastic resin. From wikipedia, Plasticisers for plastics are additive, most commonly phthalates, that give hard plastics like PVC the desired flexibility and durability. They are often based on esters of polycarboxylic acids with linear or branched aliphatic alcohols of moderate chain length. Plasticisers work by embedding themselves between the chains of polymers, spacing them apart (increasing of the "free volume"), and thus significantly lowering the glass transition temperature for the plastic and making it softer. For plastics such as PVC, the more plasticiser added, the lower its cold flex temperature will be. This means that it will be more flexible, though its strength and hardness will decrease as a result of it.

Imagine that you have a bunch of cooked spaghetti noodles laid out lengthwise. When the water in the spaghetti dries out they begin to stick to each other. If you were to grab a large handful of it and bend it, the spaghetti would most likely break. However, if we added some olive oil or butter to the spaghetti, it would be more flexible and not break. The butter or oil is getting in between the individual spaghetti strings and lubricating them.
This same concept applies to our plastic. The glycerin gets in between the amylose and dextrin molecules and keeps them from sticking together. Without the glycerin in our plastic, it would crack and shatter if we bent it, or put stress on it, but since we added glycerin- a plasticiser to it, the starch plastic is flexible.

Now that you understand how to make potato plastic, and the science behind it, go forth and spread the good news to all, so they can enjoy it themselves, and save our planets resources at the same time.
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hi i am really interested in work can
you please send me a copy of your research paper . I see that you you
are very knowledgeable with this and i need this for my science project.
please! please! i beg you. thanks

here's my email dilrajdeep1994@gmail.com
lupefiasco5 years ago
Hi, I'm doing a research project, where I'm reinforcing these plastics with natural fibers, and entering a contest with it. However, I'm having great results with reinforcement, but without it (what you are doing here), my plastics are not drying, and are still gooey after a month. I have dried the other plastics by pressing them between two glass plates, because I need a smooth surface as I am testing them with a tensile tester. I have followed your recipe perfectly in terms of materials, but could you give me some more specific temperatures in Farenheit, of what you consider "low" and "high" temperature? I think that this may be the problem. Thanks, I would really appreciate an expedient response. (alisonlyang@gmail.com)
Hello there. I am currently doing a project on bioplastics. But i face a problem as the strength of the plastic is not that strong. I have tried a few methods to strengthen it. But this way of using natural fibres is something new and i would love to try it out. Can you please send me a copy of your research paper. Please please please. My email is dilrajdeep1994@gmail.com. thank you

hello.I really like your ideas with this investigative project.. If you don't mind, may I ask you to please send me a copy of your research study for me to use as my guide because I will be conducting a research study with regards to bioplastic using squash starch and jute to plasticize it. I will greatly thank you for that. I will recognize your paper as my reference in my study. Thank you so much. This is my email add (rodniewicas@yahoo.com/ rdwicas@gmail.com)

Hey Lupe,
I really like the idea of your project. I really want to make that as our project too; however, we don't have tensile tester in our school. My plan originally is to make a plastic bag ( which I don't know how to accomplish) Next I will test the strength of the plastic bag in carrying things. I don't know how to logically do the testing in testing the strength. Can we do that without the tensile tester? I mean is testing the tensile the same with testing the ultimate strenth the plastic can handle? What can you suggest as the best step that we could take? and about the fiber thing that you add to your plastics.. what are they for? What are fibers? As I understand it they can help strengthen the plastic. Would the existence of the fiber somehow affect the biodegradability of the plastics? Cause you see, aside from the strength of the plastics, * durability* , *practicability* we also aim to test its biodegradability by burying it in soil and observing it. Do you think it can really be decomposed. I have read in the net a certain study claiming that after two weeks, she had seen her plastics decompose by fifty percent. I don't what that fifty percent mean. Could that really possibly happen? I would really appreciate if you can answer all my questions and offer my advice. I really want to succeed on this project. What makes this project hard for me is the fact that it's a group project. (whew...)
From my understanding, vegetable oils will work just fine. Plasticizers do affect the durability of plastics, but if you use the plasticizer as a control it should not be an issue if you are doing a comparative study.

Natural fibers are the individual strands that make up cotton clothing (the filaments on the threads that tear off your shirts) or that make up different types of strings. In nature, they make up plants stalks, etc. When amylose & amylopectin fuse, natural fibers will strengthen that bond. As you see in my study, the thickest, most tangled fiber did the best job of reinforcing the plastic.

I worked at a plastics company for this project, so I had access to a tensile tester. Get in touch with a nearby company or university, no doubt they will have a tester that you can use. They are easy to operate. As for the fibers, I also used a grinder at the company lab to grind my fibers down, but you can try a coffee grinder... not sure if it'll work though.

Addressing the testing if you cannot find a tensile tester-- I think that you could make bags by coating two glass plates and then connecting the bottoms of the plates? Experiment with this. I did not try making plastic bags, it is probably more difficult. You could always try a less exact method of measuring strength/durability by placing small weights inside the bags and seeing how many the bag can hold. Definitely less exact and the chance of scientific error will increase, but make do with what you have.

I have sent you the paper, let me know if you have other questions. I encourage you to seek out local plastic companies or contact professors universities. Most labs have tensile testers. Good luck.

hi i am really interested in work can
you please send me a copy of your research paper . I see that you you
are very knowledgeable with this and i need this for my science project.
please! please! i beg you. thanks

here's my email besslightyear@gmail.com

hi i am really interested in work can you please send me a copy of your research paper . I see that you you are very knowledgeable with this and i need this for my science project. please! please! i beg you. thanks

here's my email besslightyear@gmail.com

hello, please also send me the research paper at tawinligahon@yahoo.com or toweeligahon@gmail.com.........
please, please, please!
hello can you send me research paper at silverhaseo@gmail.com or mr.mime95@yahoo.com plsss
hi lupefiasco
i dont know how i could use or extract the fibers for my potato plastic
it seems to have worked for you so could you tell me?
thanks
What are glass plates? How do your glass plates look like? How do you think can I combine the bottom of the two glass plates? What's the shape of your glass plates?
Didn't see the biodegradability question, sorry. I have no experience with soil biodegradability. Look at my paper and you will see that I used hydrodegradation by placing plstics in water... didn't work incredibly well. Just try it, who knows what will happen. That's the fun of science! 50% would mean that when they massed the plastic after being buried in soil, the plastic was half of its original mass. Try it out with your plastics and let me know how it goes.
helo, lupefiasco, wat kind of natural fibers tat u add on ?my plastic is too soft and tear off when juz touching it...I wan to test my plastic on tensile test too, but it is too soft and cannot be tested by machine... do u hv the same problem as i had ?
Hi there,
You may be adding too much plasticizer, or you may just need to spread the plastic thicker. Experiment with types of plasticizer, because that will dictate those kinds of properties. I use cotton, jute, and hemp fibers in my study, and hemp performed the highest in resisting water degradation as well as in strength tests. I will share my methods with you here, feel free to ask if you have more questions.

"Phase I of the experiment involved the creation of samples for testing. A slurry of 2 tablespoons of starch and 8 teaspoons of water was created. If applicable, 6g of fiber was added and mixed into the slurry until it became relatively homogenized. Then 1 teaspoon each of glycerin and vinegar were added to the slurry. The slurry was heated at low on an electric stove, then when it began to steam, turned up to high and allowed to boil. Then the slurry was poured and spread onto two glass plates with non-stick surfaces. The plates were then pressed together to create a flat layer of plastic. This process was repeated for each fiber, and for the control plastic without fiber. After the plastic had partially solidified, one glass plate was removed and the plastic allowed to air dry until completely solidified."

"The results of the tensile testing supported the hypothesis that the hemp fiber reinforced plastic would demonstrate the greatest tensile strength. The reinforced plastic had an average tensile stress at break of 2138.63 psi. A Kruskal-Wallis test, which compares the differences among medians, conducted on the tensile strengths of hemp, jute, and cotton, and non-reinforced (control) plastics showed that the differences are statistically significant (k=10.3846, p.= 0.016).  As shown in Figure 5, the hemp-reinforced plastic was significantly stronger than the other plastics. The fiber-reinforced plastics were also significantly stronger than the non-reinforced control. As shown in Figure 6, though the hemp plastic failed quickly under tensile stress, it was a brittle failure, and the plastic held a large load."

So since the plastics suffered brittle failure, the problem was the plasticizer, and I suspect that you are having the same problems. Following these methods you should be able to create plastics that stay together and are strong.

Brandon121233 (author)  lupefiasco4 years ago
 Awesome! Finally a comment posted above the average elementary school intelligence level. Lupe if you publish a paper on this when your done would you mind sending me a copy? 
 Hey there, I've actually been long done with this project. I did well with it at state competitions in 2009, but I changed my focus to the biological aspect of plasticizers this year. I do have a copy of the paper, where would you like it sent?
hello lupefiasco!!, I am very much interested in your work. if you would not mind ,can you send me a copy of your research paper?? at rean_jean@yahoo.com . btw i am a highschool student from the phils.your efforts will surely be recognized. Thank you so much ... :DD
Hi! I hope you will still be around to see this, but do you think you could also send me your paper? I'm a conbio student and would love to work on this! luckyprincessmelody@yahoo.com Thank you so much if you are able to send it! Melody
Brandon121233 (author)  lupefiasco4 years ago
 Brandon121233@gmail.com      thanks, I'll let you know what I think about it, its always good to see other peoples ideas on the same topic 
what are fibers? What's in them that makes the plastic stronger? Where can we find them? Are those in the grocery? How does it looks like? What else can we use as fibers?
Can I just simply use vegetable oil as plasticizer since glycerine isn't available in our place?
thx 4 yor info....i hope u dont mind if i hv questions to ask u...haha...anyway, thx 4 for yor guide and tips....i'll try my best... ;)
 Sure thing, let me know. I can't promise I can tell you everything, I haven't worked on this topic for a while, so it's a little hazy. I hope to pick it up again this year though!
Hi, lupe....one more question....how long time does the (gel looks plastic)plastic takes to solidify as a real plastic (dry and hard plastic ) after u put the plastic on the flat plate ?
Less than 24 hours for me.
anyway, can I have a copy of you research paper if possible and if it's okay. ( mildredmongcupa@gmail.com)
Brandon121233 (author)  lupefiasco5 years ago
I have never really taken accurate measurements with a thermometer, just because its easier for me to just look at it and know its done. The starch changes dramatically in appearance when its done, from a gooey paste to a bubbly and very clear gel thats very sticky (look at the video to see what I mean). Sorry I can't help you more with that
RamP41 month ago

can you mix this with other starches

VeronicaM11 month ago

What if we don't have 100% Vegetable Liquid Glycerin, will it still work?And where can you buy it?

Wondering if this could hold water if I made a bowl out of it and if there are any properties at all that would leach that may be harmful.. Thanks!

besstulio4 months ago

Hi, may i asked if how did you test the degrade capability of the bioplastic? I BADLY need this for OUR INVESTIGATORY PROJECT. can you please send me your research work in my email besslightyear@gmail.com Your work is highly appreciated and praise in my project.thanks :)

ClayOgre8 months ago

I notice you have red potatoes depicted above. It's my understanding that something like a russet potato will work better for for producing starch.

I also have some doubts about how "green" the production of this plastic is. Energy is used in the harvesting and transport of the potatoes. It's used in the production and transpoert of the glycerin. It's used in the production of the plastic itself. To get the maximum "green", the potatoes would need to be locally grown. You'd also maybe want to use some sort of solar cooker instead of fossil fuels in the process process.

That being said, I do realize what you've got is more of a "proof of concept", rather than a full blown production process.

Stan1y ClayOgre7 months ago
the waste cellulose could be fermented into alcohol to use as fuel or turned into plastic its self cellulose acetate. Some potatoes could also be used to make alcohol for fuel instead of just make the plastic
ClayOgre ClayOgre8 months ago

Further thoughts.

What kind of scale do you see this being used on? We use a LOT of plastic these days. This stuff is supposed to be biodegradeable, so that implies it being used for disposable items. What sort of items? Does it make sense to expend resources to make something that is disposable?

How are these potato plants being grown? In rows? Potato towers grow more potatoes in a smaller space, but don't lend themselves to mechanized farming (yet). How are they being fertilized? Petrochemical fertilizers would tend to defeat the purpose of making "green" plastic from potaotes. But using organic methods, especially to manufacture any useful amount of plastic in a cost effect way, would present its own set of problems.

What about the water used in extracting the starch? For large scale production, thats a lot of water. Once it's been ised, now it's "polluted", albeit with a fairly harmless substsnce. Can it be used to water the potato fields?

What about whatever is left of the potato after the starch os extracted? Can ot be composted? Used for animal feed? What is the ratio of potatoes needed pounds of plastic produced?

What about using potatoes for food, vs making plastic? What is that going to do to the price/availability of potatoes in general?

Rather than being disposed of, could the plastic be recycled? Could a version be created that could be used as the raw material for 3D printer output? That might have some interesting possibilities.

There is also the spectre of Monsanto becoming involved in the whole process. GMO potatoes optimized (and patented) for plastics production. Gives me the shivers just thinking about it.

awalters1111 months ago
can you make the plastic out of old potatoes?
thx
Stan1y awalters117 months ago
potatoes that are unfit for consumption can still be made into starch or alcohol for fuel
gregstevens3 years ago
Hey Brandon! I hope you're doing well.

I just thought I'd mention that we're constantly posting answers to specific questions that people have about making bioplastic at home on the website,

http://green-plastics.net

We've had recent questions about everything from how to make home-made bioplastic waterproof, to explaining the chemistry behind why the vinegar helps improve the bioplastic that you are making.

It would be great if you  could let people know about our Q&A board in your instructable!


Brandon121233 (author)  gregstevens3 years ago
done, you get the headline spot boss! Thanks for helping with the questions.

can we use vegetable oil in stead of glycerin?

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