The term ‘plastic’ suggests that it is a single material but in fact there are thousands of plastics. What they all share is that they are polymers. They tend to be complex compounds also containing additives such as plasticisers to improve flexibility and fillers to add strength. Plastics can be thermosets, that on being heated and moulded set permanently, or thermoplastics, that can be re-melted after moulding, enabling recycling.
Natural plastics
are materials that come from plants and animals that can, with the application of heat, be moulded into forms in their natural states.
Semi-synthetic plastics
are made in a laboratory from chemically altered natural materials. Modern semi-synthetic plastics are sometimes called bio-plastics.
Synthetic plastics
are materials made in a laboratory. Although organic in origin, their molecules are not found in nature.
Composite materials
combine plastics with other materials to make use of the properties of both. They are also known as fibre reinforced plastics; the fibres can be made of plant material, fabrics, glass and carbon.
