The word plastic comes from plastikos, a greek word that means capable of being shaped. Synthetic plastics have a high plasticity. As mentioned earlier, synthetic plastics (polymers) are long chains or connected units of monomers. Think of this as a necklace of pearls. Each perl is a monomer, and linked into a chain, it becomes a polymer.

Polymers are produced in a chemical process called polymerisation. During this process, two kinds of plastics are may result: thermoplastics and thermosets.

Thermoplastics can be melted by heating and hardened by cooling several times without losing its chemical properties. This reversible property makes it easier to be moulded into many shapes and used. An example is Polyethylene.

Thermosets usually cannot be remelted and reused because it undergoes a chemical change. An example include silicone and Acrylics.