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EXAMINATION QUESTION - POLYLACTIDE - ANSWER

V. Ryan 2011

 

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Why is polylactide suitable for the manufacture of carrier bags?

 
You may wish to include reference to the following terms:
 
Renewable - Sustainable - Environmentally friendly - Polymer - Biodegradable - Bioplastic - Starch - Sugars - Resin - Sun Light - Oxygen - H20 - CO2 - Land Fill - Life Cycle
 
 
 
Sample Answer
 
The average plastic bag is manufactured from polyethylene and has a reputation of being environmentally unfriendly. This type of carrier bag can take years and even centuries to decay. In countries such as the Republic of Ireland, a plastic bag levy has been introduced, to pay for removal and collection of old plastic bags from the urban environment and countryside. Polyethylene plastic bags are a hazzard to wildlife, damage the environment and they are unsightly. For many years there has been a need for plastic bags that decay naturally and do not damage the environment, in the long term.

Polylactide is referred to as a ‘bioplastic’ because of its environmentally friendly nature. Plastics bags made from Polylactide take only five years to decompose. PLA is a renewable thermoplastic and a polymer. It is ‘processed’ from the starch of plants such as corn, sugar cane and sugar beet, making it environmentally friendly and sustainable. Polylactide is biodegradable, as it decays as a result of exposure to the ultra violet rays of sunlight and oxygen. It decomposes forming carbon dioxide and water, which present no danger to the environment.

Polylactide carrier bags can be manufactured in exactly the same way is polyethylene bags. PLA is manufactured by the fermentation of the sugars from corn or sugar beet. This produces lactic acid and after further chemical reactions, lactide forms. After more processing and polymerisation, polylactide resin is produced. The resulting resin can be injection and blow moulded, to form disposable products including ‘carrier bags’.

Most shoppers are environmentally aware. Supermarkets have made alternatives to carrier bags available, such as ‘strong life time bags’. However, many customers still prefer traditional carrier bags. The use of polylactide carrier bags gives supermarkets the opportunity to enhance their ‘green’ credentials, as well as offering a traditional carrier bag. Furthermore, the introduction of PLA carrier bags, gives the customer the opportunity to protect the environment, through its use.

For these reasons, PLA is considered highly suitable as a material for the manufacture of carrier bags.
 
 
 
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