Plastics.

Eastern Waste. management authority inc.

Plastics, first invented by Alexander Parkes in 1860, have only been widely used in the past few decades. Plastics production worldwide now exceeds 80 million tonnes a year. Australia produces about 1 million tonnes of plastic products and packaging each year.

Plastics are made from oil, gas and coal. According to the Plastics and Chemical Industry Association, "much of the raw material for plastics comes from waste in petroleum refining - some of which would otherwise be flared off (burnt) and wasted".

Plastics are polymers - long chains of molecules made up of smaller molecules called monomers.  The polymers are made in large vessels under special conditions of temperature and pressure, using special catalysts.  At this stage the polymers are in the form of resin pellets or powder.

There are about 40 different plastics or polymers used today.  Each has a different chemical composition, a different strength and durability and is suitable for different uses.  Refer to the chart below of the 7 common plastics.

There are three main ways plastics are formed into products from resin beads or powder form:

1. Injection moulding - for specially shaped objects such as cups, toys, plumbing pipes, wheelie bins.
2. Extrusion moulding - for plastic sheets, straight pipes and tubes.
3. Blow moulding - for bottles and drums.

Other techniques are used for margarine tubs, Styrofoam and biscuit trays, fibres used in fabric and insulation, pens, scissor handles, cassette covers etc.

To help identify the different plastics, manufacturers stamp a plastics code on their products.

This code is a number inside the triangular arrows, like this.

It is usually located on the bottom of a plastic container. It doesn't automatically mean the plastic is recyclable, it just tells you what 'family' of plastics it is made from. The number codes start at 1 and go to 7.

The abbreviations for these plastic types are:

1 = PET

2 = HDPE

3 = PVC or UPVC

4 = LDPE

5 = PP

6 = PS

7 = other (not specified as any one of the above groups)

At present ALL RIGID PLASTIC CONTAINRES can be recycled.

Plastics collected for recycling are sorted into their own categories, packed into bales and sent to different factories for reprocessing.  They are shredded, chopped or ground into small pieces, washed to remove labels and leftover juice, milk or whatever was contained in them, dried and melted into resin, stretched into strands and cut into beads or ground into powder. Then it's melted and moulded into shape just like new plastic is.

Some plastics are also made into fibre (material). The plastics are heated and the stretched from which they can be spun. The initial result is a fluffy fibre that looks very similar to cotton wool. From there it can be made into a large variety of materials. Typical names for plastic you will find in clothes and other fabrics are polyster, nylon, acrylic and polyurethane.

In South Australia:

Plastics that bear a deposit are sent to Statewide Recycling. They are then separated by type and by size. From there they are sent to various world markets. A large percentage is recycled in Australia, but many are also sent to places such as Asia.

Many of the category 2 and 5 plastics (HDPE & PP) are sent to Plastics Granulating Services (PGS) located at Kilburn in Adelaide. PGS pelletise the plastics which are then sold in a "ready to use" form to companies making plastic products. HDPE is regularly made into irrigation pipe, plastic sheeting and plastic bags. PP is commonly made into flowerpots and chair components.

A large variety of non-deposit plastics are sent to Plastic Recyclers of Australia who are located in Port Pirie. They recycle plastic into products such as outdoor furniture, vineyard posts and playground equipment.

When recycling any plastic containers, it is important to remove the lids.  Apart from the lids often being different types of plastic to the containers, the value for removing lids is so the plastic containers can be easily baled. Transporting containers full of air would not be economical or good for our environment.