Goal: Scouts will understand the raw materials from which plastics are made and understand that polymers are the building blocks of plastics.
Supplies: colored paper clips
Procedure: Each paper clip represents a monomer. Each color represents the same monomer. Another color is a different monomer. Make a chain of clips to form a single straight polymer of the same color. Move the polymer chain around to see how easy it is to move. Create two polymer lines parallel to each other. Crosslink the polymer by taking 1-2 paper clips and connecting the 2 polymer chains (think of an “H” formation). Is it easier to move the single polymer chain or the cross-linked chain?
The smaller molecules that come together to form polymers are called monomers—small units that link together over and over to form a large polymer. Think of monomers like paper clips that link together to form a polymer chain. Polymers are many monomers linked together.
Some raw materials (feedstocks) used to make plastics include crude oil, natural gas, corn, sugar cane or castor beans
To make plastics, chemists and chemical engineers must do the following on an industrial scale:
(From How Stuff Works1)
First, they must start with various raw materials that make up the monomers. Ethylene and propylene, for example, can come from crude oil, which contains the hydrocarbons that make up the monomers. The hydrocarbon raw materials are obtained from the "cracking process" used in refining oil and natural gas. Once various hydrocarbons are obtained from cracking, they are chemically processed to make monomers used in plastics.
Next, the monomers undergo polymerization reactions in large polymerization plants. The reactions produce polymer resins, which are collected and further processed. Processing can include the addition of plasticizers, dyes, and flame-retardant chemicals. The final polymer resins are usually in the forms of pellets or beads, sometimes called nurdles.
Finally, the polymer resins are used to manufacture plastic products. They are heated, molded, and allowed to cool. There are several processes involved in this stage, depending upon the type of product.
Outcome: Students understand that plastics are made up of monomers joined together to form polymers.
1 Craig Freudenrich, P. D. (2020, January 27). How plastics work. HowStuffWorks Science. Retrieved September 7, 2022, from https://science.howstuffworks.com/plastic5.htm