What is Plastic Made of?

Plastics are an indispensable part of modern life. From water bottles, household containers, and kitchen appliances, to automobile parts and accessories, plastics have found numerous uses and applications. They are basically defined as polymers, as they are composed of a long chain of smaller molecules, which are known as monomers. Monomers of plastics can be natural or synthetic compounds.

A polymer is defined as a chain of repeated simple monomers. It can consist of several elements, such as carbon, hydrogen, oxygen, chlorine, nitrogen, fluorine, silicon, sulfur, and phosphorus. In general, different kinds of monomers are used to manufacture different types of plastics. The monomers used for making this material are usually extracted from organic substances, like oil and the sap of certain trees. But presently, they are mainly derived from petrochemicals.

A wide range of products are obtained from petrochemicals. Fuel, gasoline, diesel, and various types of lubricants are all derived from petrochemicals. Propane and ethane are the two basic substances that can be found in oil, which are used for manufacturing plastics. Other than petrochemicals, corn and other biomass can also be used for making this material. For this, corn kernels are first milled and then dextrose is added to them. These are then allowed to ferment, and in the process, lactic acid and a type of plastic, known as polyactide polymer are obtained as byproducts.

The entire process starts at the point when petroleum is drilled and then shipped to the refineries, where crude oil or petroleum and natural gas are refined to produce a large number of petrochemical products. Propane and ethane are also extracted from crude petroleum, which are then placed in high temperature furnaces. In other words, both the substances are subjected to cracking, in order to break them into smaller unsaturated hydrocarbons. Cracking of ethane and propane yields ethylene and propylene.

Both ethylene and propylene are then placed in a reactor, where they are combined with a catalyst. This process results in the formation of 'fluff', which is nothing but the powdered polymer. The 'fluff' is combined with additives in a continuous blender. There are various types of additives, which can be added to the 'fluff', in order to create the desired quality in the final product.

After combining with the additives, the polymer is fed to an extruder in order to melt it. The molten polymer is then allowed to cool, after which it is introduced to a pelletizer. A pelletizer is designed to compress and mold a material into tiny pellets. The plastic pellets obtained thus are used to manufacture a wide range of products with the help of various processes, like extrusion, injection molding, and blow molding.

It is true that plastics have become an integral part of the modern world. But it should be kept in mind that the products made from this material are not biodegradable. This is the reason why, its increasing use has become a major environmental concern. So, it important to limit the use of plastic products, and recycle them as far as possible.