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Becky Kriger

Biopolymers and Bioplastics - 0 views

  • Biopolymers are polymers which are present in, or created by, living organisms. These include polymers from renewable resources that can be polymerized to create bioplastics. Bioplastics are plastics manufactured using biopolymers, and are biodegradable.
  • There are two main types of biopolymers: those that come from living organisms; and, those which need to be polymerized but come from renewable resources. Both types are used in the production of bioplastics
  • Biopolymer Natural Source What is it? Cellulose Wood, cotton, corn, wheat, and others This polymer is made up of glucose. It is the main component of plant cell walls. Soy protein Soybeans Protein which naturally occurs in the soy plant. Starch Corn, potatoes, wheat, tapioca, and others This polymer is one way carbohydrates are stored in plant tissue. It is a polymer made up of glucose. It is not found in animal tissues. Polyesters Bacteria These polyesters are created through naturally occurring chemical reactions that are carried out by certain types of bacteria.
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  • Biopolymer Natural Source What is it? Lactic Acid Beets, corn, potatoes, and others Produced through fermentation of sugar feedstocks, such as beets, and by converting starch in corn, potatoes, or other starch sources. It is polymerized to produce polylactic acid -- a polymer that is used to produce plastic. Triglycerides Vegetable oils These form a large part of the storage lipids found in plant and animal cells. Vegetable oils are one possible source of triglycerides that can be polymerized into plastics.
  • Using Fermentation to Produce Plastics Fermentation, used for hundreds of years by humans, is even more powerful when coupled with new biotechnology techniques.
  • Today, fermentation can be carried out with genetically engineered microorganisms, specially designed for the conditions under which fermentation takes place,
  • Fermentation, in fact, is the process by which bacteria can be used to create polyesters. Bacteria called Ralstonia eutropha are used to do this. The bacteria use the sugar of harvested plants, such as corn, to fuel their cellular processes. The by-product of these cellular processes is the polymer.
  • Lactic acid is fermented from sugar, much like the process used to directly manufacture polymers by bacteria. However, in this fermentation process, the final product of fermentation is lactic acid, rather than a polymer. After the lactic acid is produced, it is converted to polylactic acid using traditional polymerization processes.
  • Plants are becoming factories for the production of plastics. Researchers created a Arabidopis thaliana plant through genetic engineering. The plant contains the enzymes used by bacteria to create plastics. Bacteria create the plastic through the conversion of sunlight into energy. The researchers have transferred the gene that codes for this enzyme into the plant, as a result the plant produces plastic through its cellular processes. The plant is harvested and the plastic is extracted from it using a solvent. The liquid resulting from this process is distilled to separate the solvent from the plastic.
  • Currently, fossil fuel is still used as an energy source during the production process. This has raised questions by some regarding how much fossil fuel is actually saved by manufacturing bioplastics. Only a few processes have emerged that actually use less energy in the production process.
  • Energy use is not the only concern when it comes to biopolymers and bioplastics. There are also concerns about how to balance the need to grow plants for food, and the need to grow plants for use as raw materials. Agricultural space needs to be shared. Researchers are looking into creating a plant that can be used for food, but also as feedstock for plastic production.
  • Biopolymers and bioplastics are the main components in creating a sustainable plastics industry. These products reduce the dependence on non-renewable fossil fuels, and are easily biodegradable. Together, this greatly limits the environmental impacts of plastic use and manufacture. Also, characteristics such as being biodegradable make plastics more acceptable for long term use by society. It is likely that in the long term, these products will mean plastics will remain affordable, even as fossil fuel reserves diminish.
Becky Kriger

Biodegradable plastics made from corn - 0 views

  • Biodegradable plastics have already been created by using proteins from plants such as corn or soy. But they were not strong enough to be used by the industry. Now, researchers at Iowa State University have found a way to reinforce these biorenewable plastics. They are using high-powered ultrasonics to reinforce the plastics with nanoclays.
  • But how biodegradable plastics can be made with corn proteins? Grewell keeps a plastic model of a molecule looking like a ball. That's about the shape of a soy or corn protein […] Then he unfolded the model into a long, straight loop. That's what happens when researchers add some glycerin — a byproduct of biodiesel production – and some water to the molecule.
  • Nanoclays are clays from the smectite family which have a unique morphology: they form platelets about 1 nanometer thick and 100 nanometers in diameter. Below is an example of the structure of one nanoclay raw material named montmorillonite.
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  • Apparently, it's difficult to use these nanoclays. So the researchers turned to "high-powered ultrasonics — high-frequency sound waves too high for human hearing – to separate and disperse the platelets."
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