How Plastics Are Made

Plastic Pollution that ends up in the sea. 
Photograph: Paulo Oliveira/Alamy Stock Photo


Plastic is made up of elements such as carbon, oxygen, hydrogen, chlorine, sulfur, and nitrogen. Initially, plastic was made from natural materials such as animal horns, shellac (small insect secretions), and patchwork rubber.

Plastic material can be divided into 2, that is:

  • Thermoplastic 
  • Thermoset

The most important plastic materials are:

- Polypropylene (PP) - carpet

- Polyvinyl chloride (PVC) - pipe

- High Density Polyethilene (HDPE) - bottle

- Linear Low Density Polyethilene (LLDPE) - film

- Low Density Polyethylene (LDPE) - film

- Polyester, thermoplastic (PETE) - soft drink bottle

- Polystyrene (PS) - cassette

- Phenolic - plywood glue


In 1869, the first synthetic plastics were made of cellulose, which is a natural material derived from plants. Wesley Hyatt, an American inventor discovered that cellulose nitrate can be made into plastic by adding camphor. The first commercially recognized synthetic plastic was called celluloid. This plastic is used as a material to make combs, dentures, sunglasses frames, etc.

How Plastic Is Made
Source: Youtube


Plastic containers, boxes, and bins are widely used around the world to store a wide variety of liquid and solid products. The revolutionary invention took place in 1951, two young chemists discovered polypropylene and polyethylene. This discovery paves the way for the various plastic products we know today. Plastic has become a part of our daily lives. Plastic can be made from several sources, including:

Manufacture of Plastic from Petroleum
First, crude oil freshly pumped out of the ground is transported to the oil refinery. At the oil refinery, crude oil must go through a purification process along with natural gas. Ethane, propane, and various other petrochemical products are produced by the purification process. Further ethane and propane are broken down using a high temperature furnace, ethylene and propylene are formed from this process.

In reactors, the formed ethylene and propylene are combined with catalysts to form a powder-like substance. This flour-like substance is similar to powder detergent, this substance is a plastic polymer. In a continuous mixing, some additives are combined with polymers, followed by an extrusion process, in which the plastic is in liquid form.

The plastic in liquid form is left to cool and then the pelletizer is used to form the polymer into small pellets. These plastic pellets are then shipped to customers. Manufacturers of combs, plastic bottles, dentures, etc. buy these plastic pellets to be used as materials for making their products.

Making Plastic by Adding Carbon Dioxide
It is amazing that plastics can be made using petroleum. But it takes a lot of petroleum to make plastic. Various efforts are being made to prevent the depletion of these important resources. In December 2009, the Novomer company announced the commercialization of polypropylene carbonate (PPC) materials using a combination of carbon dioxide and petroleum. By adding carbon dioxide, the petroleum needed for plastic production is reduced by half.

Manufacture of Plastic from Corn
The carbohydrate sugar found in corn can be used to make a plastic called polylactide polymer. The invention of plastic made by corn has reduced our dependence on non-renewable petroleum. Plastics made from corn will melt when heated to more than 114 ° C, therefore plastics made from petroleum are still used today.

In addition to corn, plastic can also be made with oranges. Scientists are still looking for compounds that can replace petroleum in the process of making plastic. Hopefully in the future we will find renewable plastic material as a replacement for non-renewable petroleum. Until then, remember to always recycle plastic.



References

American Chemical Society. 2020. Poylpropylene And High-Density Polyethylene - National Historic Chemical Landmark - American Chemical Society. [online] Available at: <https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/polypropylene.html> [Accessed 28 July 2020].

CBC. 2020. Scientists Create Plastic That Takes Just Weeks To Break Down — But Don't Raise Your Water Bottles Yet | CBC News. [online] Available at: <https://www.cbc.ca/news/technology/scientists-make-plastic-carbon-dioxide-sugar-1.4160073> [Accessed 28 July 2020].

Encyclopedia Britannica. 2020. Celluloid | Synthetic Plastic. [online] Available at: <https://www.britannica.com/technology/celluloid> [Accessed 28 July 2020].

Garden, H., HowStuffWorks, Science, Science and Science, 2020. What Is Corn Plastic?. [online] HowStuffWorks. Available at: <https://science.howstuffworks.com/environmental/green-science/corn-plastic1.htm> [Accessed 28 July 2020].

Plasticseurope.org. 2020. How Plastics Are Made :: Plasticseurope. [online] Available at: <https://www.plasticseurope.org/en/about-plastics/what-are-plastics/how-plastics-are-made> [Accessed 28 July 2020].

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