Where do plastics come from?

where-do-plastics-come-from
coal

From raw material to finished product

Most plastics are derived from petrochemical feedstock, which in turn originates from oil, natural gas or coal. In South Africa the gas comes from coal.

1. Coal

Sasol makes ethylene and propylene gas from the refining of coal at the factor in Sasolburg.

2. Polyethylene and Polypropylene

Sasol Polymers and Safripol polymerise the ethylene and propylene into polymers called Polyethylene and Polypropylene (PP).  These polymers are now in a powder form.  Hosaf polymerise PET from imported chemicals.

polymers3. Polymer [raw material]

In the granulation plant additives and fillers could be added to the powder and the compound is then granulated and bagged – ready to be sold to the converters, who in turn manufacture products for the packaging, building, agricultural, mining, automotive sectors, etc. This is know as virgin material.

4. Plastics to finished products

The most common processes used in the plastics industry required specialised equipment which melt, compress and cool the plastic granules during the forming process.  Some of the processing
techniques are:

  • blow moulding
  • extrusion
  • injection moulding
  • rotational moulding and
  • thermoforming

 

Content and images courtesy of Plastics SA