Most polymers are obtained from crude oil often found deep within the Earth’s crust. It is accessed by drilling, which can be a costly and messy process. Some polymers can be derived from natural sources, such as plants. The most common plant-based polymer used in schools is polylactic acid (PLA), which is commonly used in a 3D printer. PLA is obtained from corn starch - the corn is fermented to produce lactic acid, which is polymerised to produce polylactic acid.
Bioplastics are being continually developed to combat the environmental concerns related to the non-biodegradable properties of plastic polymers.
The process used to produce the common polymer polythene:
When crude oil is heated, many different chemicals are vented off from the heating column. The thick and dense material bitumen, used for road surfacing, is vented off from the hottest part of the column at the base. Lighter, less-dense gas and petrol are vented at the cooler part of the column towards the top.