What are plastic bags made from?

Plastic bags are typically made from polyethylene, which is a common and cost-effective plastic material. Depending on the specific purpose and application, polyethylene can be divided into two types: high-density polyethylene (HDPE) and low-density polyethylene (LDPE).

High-density polyethylene (HDPE) is often used to produce thicker and more sturdy plastic bags such as shopping bags and garbage bags, as it offers higher strength and durability while maintaining rigidity.

On the other hand, low-density polyethylene (LDPE) is more suitable for manufacturing flexible, lightweight bags that are easy to fold and carry, such as bread bags and produce bags, due to its softness and elasticity.

How does the polyethylene bag making machine work?

1. Material preparation: Polyethylene resin pellets are loaded into a hopper on top of the machine, where they are heated and melted.

2. Extrusion: The melted polyethylene is then pushed through a long, narrow die by a rotating screw, which creates a continuous tube of plastic film.

3. Inflation: Air is blown into the center of the tube, which inflates it into a bubble. The size of the bubble determines the width of the film.

4. Cooling: The bubble-shaped film is then passed over a series of cooling rollers, which cool and solidify the plastic.

5. Flattening and folding: The cooled film is then flattened and folded several times to create multiple layers of thin, flexible film.

6. Slitting and sealing: The flattened film is slit into sheets of the desired width, and the edges are sealed and cut to create individual bags.

7. Collection and packaging: The bags are collected and packaged for distribution.

The process is automated and controlled by a computer, which ensures consistent quality and high production efficiency. The speed and temperature of the machine can be adjusted to accommodate different types of polyethylene and bag sizes. Additionally, the machine may incorporate accessories such as printers and punching units to add logos or holes to the bags.

What can I do with the plastic bags I have at home?

Reuse or recycle them:

• Reuse plastic bags you have accumulated at home as garbage bin liners, for clothing storage, for carrying wet things and for freezing food, or to pick up after pets.

• Take your plastic check-out bags to participating retailers such as Coles or Woolworths for recycling, as these cannot be placed in your yellow lidded household recycling bin.