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Polymers and the environment: Polymers are widely known as plastics among people. However, the big image on plastics for the most is not a positive one, probably due to some of the environmental issues that cased by various polymers. It should be noted that not all polymers have a negative environmental impact. Thus, it would be better to have a general understanding of polymers, their uses, advantages and disadvantages, and the modifications that are possible to improve the properties of the polymers for the better. |
With the advancements of science, a variety of polymers are emerging everyday. Scientists are working relentlessly to improve the properties of existing polymers as well as to find new variety of polymers. Articles made from synthetic polymers can be found in every area of life. For example, polyvinyl chloride (PVC) is used in toys, pipes, fittings, sidings, wall and floor coverings, cable coatings, medical devices etc. One of the widely used consumers plastic is polyethylene terephthalate (PET). PET is used mostly to make bottles, food packaging containers etc. Polylactide, a biodegradable synthetic polymer, derived from renewable resource corn, has found wide variety of applications in products including disposable grocery bags, cutlery, as well as in apparel and clothing. Details of most of these polymers are given in other sections of this site. |
Recycling of plastics: Most plastics can be recycled to make useful materials after their intended use. To make it easier to separate and identify various articles made from different polymers, universal recycling coding system has been developed by the Society of Plastic Industry. According to the system, products are coded as follows: Number 1 for PET, 2 for High density Polyethylene((HDPE), 3 for polyvinyl chloride (PVC), 4 for Low Density Polyethylene (LDPE), 5 for polypropylene (5), 6 for polystyrene (6), and 7 for other polymers such as acrylic, polycarbonate, nylon etc. To complete the code, these numbers are enclosed by a rounded triangle made from arrows that cycle clockwise. More often an acronym that represents the plastic also is placed below the code. Among the various different plastics used in the world, only PET, HDPE and PS are the more-often recycled plastic. However, arguments are still going on the worthiness of recycling, as it emits more CO2 to the environment than when burying in landfills. Thus, with increasing environmental issues due to stockpiling plastic wastes in landfills, people around the world are paying more attention to reduce the production and usage of non-degradable plastics. In addition to recycling, reuse of plastic bags, using other types of containers made from environmentally friendly materials such as clay and ceramic, metals should be encouraged in the general public. In addition, scientists around the world are finding ways to make environmentally friendly plastics that can compete with petroleum based polymers. Special attention has given to use renewable resource agricultural based raw materials to make polymers which usually degrade in landfills without eliminating toxic materials to the environment. One of the mostly used raw materials is corn, beet and other agricultural sugars which by fermentation could convert to make the starting material for the polymer. In addition, scientists are using bacteria which could grow the polymer in themselves. |