★ There are to types of plastics in Chemistry ::
1-Thermosetting plastics : those plastics which can be repeatedly moulded like that of buckets in your house.
2-Thermoplastics : those plastics which can only be moulded once in their manufacture and afterwards cannot be softened like plastic of switches in your house.
★ If you sell an old used bucket, its worth something still, but the switch isn't worth anything as you cannot reshape it.
★ Thank God chewing gum is a thermoplastic otherwise like polythene bags, the same gum would also be reused possibly a thousand times !