Some plastics are light and soft and can be filled with air bubbles to make an ideal packing material.
Vacuum molding involves using a vacuum to suck a sheet of plastic into a mold.
Extrusion molding involves heating plastic pellets and forcing them through a nozzle to give the required shape. Plastic pellets Extrusion molding is used to produce continuous shapes such as pipes. Injection molding is used to produce non-continuous forms such as bowls.
Plastics are synthetic (man-made) materials that can be easily shaped and molded.
Most plastics are polymers (see new materials). The structure of polymer molecules gives different plastics different properties.
Long chains of molecules that slide over each other easily make highly flexible plastics such as polythene. Tangled chains make rigid plastics such as melamine.
Typically plastics are made by joining carbon and hydrogen atoms. These form ethene molecules, which can be joined to make plastic called polythene.
Many plastics are made from liquids and gases that are extracted from crude oil.
Thermoplastics are soft and easily molded when warm but set solid when cool. They are used to make bottles and drainpipes and can be melted again.
Thermoset plastics, which cannot be remelted once set, are used to make telephones and pan handles.
Blow molding involves using compressed air to push a tube of plastic into a mold.