what's ur addy? there is a diagram that goes with it
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[FONT="]Biopolymer – Polylactic Acid[/FONT]
[FONT="]A biopolymer is a naturally occurring polymer produced by living organisms including plants, animals and micro-organisms. Many biopolymers have been used by humans since ancient times. But there is increasing interest in developing new biopolymers with special properties and which have the benefit of being both biodegradable and renewable. Polylactic acid (PLA) is a biopolymer and has shown great potential.[/FONT]
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[FONT="]Waste from potatoes, corn and maize contain starch, which can be broken down into simple sugars such as lactose and glucose by yeast. The lactose is then fermented by lactic bacteria (
Lactobacillus) to produce lactic acid. Lactic acid can then undergo condensation polymerisation to form polylactic acid (PLA). [/FONT]
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[FONT="]Properties of PLA Relative to its Products[/FONT][FONT="][/FONT]
[FONT="]PLA can be used to make: [/FONT]
[FONT="]* Disposable packaging and utensils for food[/FONT]
[FONT="]* Medical equipment[/FONT]
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[FONT="]The properties of PLA allows for it to be used to produce products. The monomers, lactic acid are connected together by their hydroxyl groups (hydrogen bonding) making the resulting polymer polylactic acid, the final product is relatively strong and resistant to liquids. [/FONT]
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[FONT="]PLA has been successfully used in the medical field. During surgery, temporary sutures are fixed to the body; PLA’s composition can be made strong to allow the body to recover from injury before it begins to decompose from the enzymes in the body.[/FONT]
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[FONT="]PLA can also be made to be more flexible and are especially suited for short-lived packaging. For example liquid containers along with packaging for fruit and meat, this is because it maintains its strength while being used. Britain uses the biopolymer to serve as sandwich packaging.[/FONT]
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[FONT="]Advantages[/FONT]
[FONT="]PLA has a range of characteristics and is therefore a very versatile biopolymer. It can be designed to biodegrade quickly or last for years, depending on the composition and quality. Additionally, PLA possesses an extraordinary stability, as well as an extremely high transparency. Its thermoplastic nature enables efficient and straightforward processing on conventional machines. PLA decomposes once exposed to heat and naturally occurring enzymes, which means that the packaging will not further the effects of landfill and the health hazards to wildlife. It also provides an effective asset to the medical field, the items decompose once the patient has recovered.[/FONT]
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[FONT="]Disadvantages[/FONT]
[FONT="]However, PLA also has disadvantages. The plastic softens at a temperature of about 60 degrees Celsius, which limits its suitability for the production of cups for hot drinks. Yet with the addition of heat resistant polymers and fillers, can result in greater heat stability.[/FONT]
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[FONT="]PLA is deemed to be extremely cost-efficient and more viable as an alternative to mass plastics. The world’s first large PLA production plant was put into operation in 2002 in the United States with an annual capacity of 140,000 tons.[/FONT]
