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your home-made bioplastic project!

This video shows you how to make starch-based plastic in your own kitchen, from household ingredients. Give it a try, and make eco-friendly plastic yourself!

You can also go to YouTube to view it:

Original Version: http://www.youtube.com/watch?v=5M_eDLyfzp8
Extended Version: http://www.youtube.com/watch?v=LskPNBvbuqM

Here is a transcript of the original video:

Hi my name is Brandon Sweeney and I’m going to show you how to 
make some bio plastic in your kitchen. Bioplastics are a form 
of plastics derived from renewable biomass sources, like 
vegetable oil, or corn starch, rather than conventional plastics 
which are made from petroleum. Now some of you may be wondering 
why anyone would want to make bio plastic. 

Things made with conventional plastics all have one common flaw 
and that is they all are made using petroleum based plastics. 
Worldwide we produce about 100 million tons of petroleum plastic 
per year. To make these plastics we use about 7 million barrels
of oil per day. Now imagine that number dropping to zero. With 
the help of bio plastics, one day that may be a reality.

So before we begin, let’s have a brief review on the chemistry 
of polymers. A polymer is the main building block of all 
plastics. Think of it as a long chain of large molecules also 
called monomers. An ideal plastic would have very long straight 
polymer chains allowing it to be strong and flexible. Starch is 
made of two basic components: amylose and amylopectin. Amylose 
is a very long and straight polymer like we want; amylopectin 
on the other hand is a branched and short polymer meaning it 
will yield brittle and weak plastic... not good. There are two 
things we will be doing to enhance the properties of our plastic. 
The first is a simple technique called acid hydrolysis. By adding 
a small amount of vinegar to the plastic, we can break up some of 
the branches of the amylopectin which otherwise would have made 
it brittle. Secondly we will be adding a plasticizer. The easiest 
to obtain from a drug store or grocery store is called glycerin. 
Glycerin acts like a lubricant at the molecular level, imagine a 
bowl of sticky pasta that you add butter to so that it doesn’t 
all stick together. If you want very pliable plastic for a bag 
for instance, you would add more glycerin, and if you wanted
stiff plastic then you would add less glycerin. So now that you 
know how everything works, let’s go make some.

First get a pot, silicon spatula, a stove or hot plate, a 
tablespoon and teaspoon, water, vinegar, glycerin, and finally 
some starch. I've found that tapioca starch works the best, but 
almost any kind of starch will work, for this experiment I will 
be using potato starch. Before you start get either some aluminum 
foil or a silicone heat pad like this so you have something to 
spread your plastic on for it to dry. You can also make molds to 
inject the plastic into but for now we'll keep it simple. 

Measure out 1 tablespoon of cornstarch, 4 tablespoons of cold 
water which I already pre-measured, 1 teaspoon of glycerin, and 
1 teaspoon of vinegar, add everything to the pot. Turn the heat 
on to medium and begin stirring, keep heating and stirring until 
the mixture turns from cloudy white to clear, watch how the starch 
makes a transformation from liquid to a goopy like gel. This is 
called gelatinization.  Now turn the heat up a little bit and keep 
stirring rapidly until it is completely clear. Quickly pour your 
plastic onto the cooling sheet of your preference. Depending upon 
the humidity in the air it should dry in about a day. When it’s 
dry you can do whatever you want with it.