What is Plastic?

Jun 7, 2023

Plastic is all around us. It forms much of the packaging for food and drink. For many of us it is throughout our homes, our work place, our cars, our buses, trains and planes. It can be found in our clothing, contact lenses, teeth, computers, phones, toys and house hold construction, the list goes on and on.

Plastic is versatile, light weight, flexible, moisture resistant, durable, strong and relatively inexpensive. It can be chemical resistant, clear or opaque, and practically unbreakable. These are wonderful useful qualities. Plastic plays many important roles in life on earth, but the wide spread use of plastic is also causing unprecedented environmental problems for humans and animals alike, on land and in our oceans.

The term “plastic” derives from the Greek “plastikos” meaning fit for moulding and “plastos” meaning moulded. In a broad sense plastic can be moulded and formed into many different shapes using a variety of plastic machinery such as injection or blow mounding to various extrusion processes like pipe and film.

The raw hydrocarbon material for most plastics is derived from unsustainable fossil fuels like petroleum, natural gas and coal.

Plastics are polymers which are basically molecules made up of many molecular units known as monomers. Monomers of hydrogens and carbons which are linked together in long chains to form plastic polymers. When the virgin polymer is manufactured, these chains are long and strong. Every time the polymer is recycled, these chains become shorter and weaker, but this does not mean the polymer cannot be recycled and reused. By simply adding additives the recycled plastic can be used in a variety of long term products such as in the construction of houses and for example, plastic shopping bags are recycled and manufactured into black irrigation piping. After 6 to 8 years in the field these pipes are recycled again and made into a new batch of irrigation pipes. This cycle can go on and on.

The length and structural arrangements of the polymer chains in part determines the properties of the plastic. Densely packed polymers can create ridged plastics like high density polyethylene HDPE used to make milk bottles, whereas loosely packed densities lead to softer more flexible plastics known as low density polyethylene LDPE used in food packaging such as the plastic bag you buy your tomatoes in. They are both very easy to recycle and can be mixed together during the recycling process as they are both from the same ethylene family and if equal parts are used the recycled pellets are then known as a medium density polyethylene which in turn can be used to manufacture irrigation piping. It is important to note that not all plastics can be mixed together during recycling as their molecular structures are not the same. If this does occur, the material is deemed useless, so it is important that all plastics are sorted before they are recycled.

Environmentally, plastic is a growing disaster. Most plastics are made from petroleum or natural gas, non-renewable resources extracted and processed using energy-intensive techniques that destroy our fragile ecosystems. The manufacture of plastic, as well as its destruction by incineration pollutes air, land and water and exposes workers to toxic chemicals including carcinogens. The idea of using landfill sites is also not the answer as it will not break down over time.

Plastic should be used wisely and we are all responsible for the safe recycling of it into durable long term products which can be recycled over and over into new products.