So you have done or were interested in my first instructable on potato plastic and now your looking for something that will yield better results and a little more danger, well here it is. First and foremost I strongly recommend that you approach this project only if you are willing to accept some safety rules, and I will go over those in another step. The basic premise behind making a starch based plastic is to get a starch crammed full of polymers and nothing else, as impurities would detract from the strength properties we want. To do this we are going to have to enter into the realm of modified food starches. For this instructable we will be using a starch that has been modified to have an amylose content of 70% as opposed to the normal 20% found in most starches. The product is called Hylon VII from National Starch Food Innovation. The reason we want a high amylose content is because amylose is "is a planar polymer of glucose linked mainly by hydrogen bonds. It can be made of several thousand glucose units. It is one of the two components of starch, the other being amylopectin". So basically it makes really long polymer chains (good), and if you don't fully understand this go check out my first instructable on Potato Plastic. There is a catch 22 however that puts us in quite a pickle metaphorically speaking, go to step 1 to discover this conundrum.
Heres a video of me doing some strength tests of thick and film-like pieces of my awesome plastic
Heres a video of me doing some strength tests of thick and film-like pieces of my awesome plastic
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Signing UpStep 1: The pressure is on
The starch we will be using: Hylon VII, has a 70% amylose content. The problem is that as the percent of amylose in starch increases, so does the gelatinization temperature. What does that mean? Wikipedia kindly says that "Starch gelatinization is a process that breaks down the intermolecular bonds of starch molecules in the presence of water and temperature and allows the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. Penetration of water increases randomness in the general structure and decreases the number and size of crystalline regions. Crystalline regions do not allow water entry. Heat causes such regions to be diffused, so that the chains begin to separate into an amorphous form." The bad news is that the temperature difference that is needed is rather large. The exact requirements are: "HYLON VII requires higher cooking temperatures than conventional corn starch to adequately gelatinize. Super atmospheric cooking temperatures are required, typically 310-340oF (154-171oC) depending on the solids level of the formulation being used." Hmmmm how can we increase the boiling point of water to 154 Celsius? The answer: increase the atmospheric pressure. With those handy math skills that you learned at one point, you might be able to do the calculations to find out what pressure is needed. But why waste your time when I am going to tell you that it is pretty close to 52 psi and 55-60 psi just to make sure we get it to fully gelatinize. So if you have access to a high pressure autoclave then your in business, if not your going to have to do it the dangerous way. Be cool my babies, we're on to step 3.
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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.
You can make other plastics out of the extracted cellulose, though I don't know enough to say exactly how.
problem #2 crap like that gets leaked to the techie press all the time, and I don't buy it for a second. First because there is no research paper associated with that story, thus no supporting evidence. Secondly because its from a college that has little or no know research coming out of it. Finally simply because the story was first reported three years ago, and three years later not even a peep has been mentioned about a start up company or patent being produced from this "breakthrough".
"Flammable" is potentially a major understatement, depending on what form it is in.
As for the tech press, you're probably right. I bet you can get them to publish anything of the form "Nano(noun) (noun)". Wacky news libs!
In my opinion, small colleges don't get good publications even if they do produce good research; and large colleges get away with producing crap all the time (not that they don't produce good stuff too). MIT ran a study of this effect; while I don't have a link handy this is more or less the same thing (and hilarious): http://pdos.csail.mit.edu/scigen/ (Warning: Not thesis supervisor safe)
But yeah, no research paper = no science and makes baby Newton cry.
thanks again