domingo, septiembre 17, 2006

Polymers and Packaging

Choice of material is a key element in design. Plastics have enjoyed success because of the range of properties they offer the designer: lightness, durability, design flexibility, good impact resistance, and heat, corrosion and electrical resistance.While plastics account for only 4% of all commercially extracted oil and natural gas, questions have been raised about the substitution of materials made from more sustainable sources. One option has been the production of plastics using bacteria and plants.Very small quantities of such plastics are being produced. Some of these are biodegradable: they will break down on disposal. However, these 'bioplastics' have their own environmental impacts. The energy required to produce a kg of biodegradable plastic from genetically-modified corn is 300% greater than that required to make a kg of polyethylene, derived from natural gas. Such figures point to the need for caution in claiming that such products would reduce the use of fossil fuels.Life Cycle Assessment techniques enable analysis of the energy and emissions impacts when different materials are used to produce equivalent products or packs. Plastics products often compare favourably to alternatives in such analyses due to the strength and lightweight nature of many polymers.

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