Impact of Polymers and Plastics

Plastics and the environment

Although plastics have had a huge impact globally, there is also an environmental price that has to be paid for their use. The following are just some of the ways in which plastics can cause damage to the environment.

1. Waste disposal

   Plastics are not easily broken down by micro-organisms and therefore most are not easily biodegradeable. This leads to waste disposal problems.

2. Air pollution

   When plastics burn, they can produce toxic gases such as carbon monoxide, hydrogen cyanide and hydrogen chloride (particularly from PVC and other plastics that contain chlorine or nitrogen).

3. Recycling

   It is difficult to recycle plastics because each type of plastic has different properties and so different recycling methods may be needed for each plastic. Some plastics can be remelted and re-used, while others can be ground up and used as a filler. One of the problems with recycling plastics is that they have to be sorted according to plastic type. A list of some of the different types and their identification codes are given in the table below. Alternatively, plastics should be re-used. In many countries, shoppers must now pay for plastic bags. This encourages people to collect and re-use the bags they already have.

PIC	Plastic type	Properties	Uses	Recycling
	polyethylene terephthalate	very clear high strength barrier to gas barrier to moisture	water bottles peanut butter jars mouthwash bottles	can recycle most places
	high-density polyethylene	very stiff high strength barrier to moisture allows gas through	yoghurt tubs detergent bottles cereal box liners	can recycle most places
	polyvinyl chloride	can be blended easily high strength very toughness	detergent bottles medical equipment piping	very rarely recycled
	low-density polyethylene	very flexible high strength barrier to moisture	clothing squeeze bottles bread bags	not often recycled
	polypropylene	high strength resistance to heat barrier to moisture	syrup bottles plastic caps straws	fairly easy to recycle
	polystyrene	many uses very clear is easily formed	egg cartons disposable cups take-away boxes	fairly easy to recycle
	other	dependent on combination of polymers	large containers sunglasses computer cases	often not recycled

Table: The plastic identification code (PIC), type, properties and uses of various commonly used plastics.