Introduction+to+Synthetic+Polymer+Identification

You’ve heard of the //Stone Age//, the //Iron Age// and the //Bronze Age//, right? Perhaps the best way to describe our modern age is by calling it the //Polymer Age// because synthetic polymers, also known as plastics, are so essential now to our way of life.

A polymer is a long molecule formed from hundreds or even thousands of smaller organic molecules called monomers. An organic compound is one that contains carbon, and indeed, the backbone of all polymers is composed of many carbons. Carbon is unique because it is the only element that can bond to itself to form chains that are hundreds of atoms long! Living organisms are made of natural polymers like proteins and nucleic acids, but plastics are man-made or synthesized, hence the name, synthetic polymer.

There are many types of synthetic polymers now being manufactured. One of the world’s most widely produced plastics is polyethylene, which is used to make things like grocery bags, milk bottles and food containers. Polyethylene is a long chain of monomers called ethane. Another type of polymer, polystyrene, is made from the monomer, styrene. This is used in insulation or furniture. Polyvinyl chloride, more commonly known as PVC, is made from the monomer, vinyl chloride. One might see PVC in rainwear, pipes or plastic seat covers.

In this lab, we will compare some physical and chemical properties of different plastics. These properties are a result of the polymer’s chemical structure, such as the length of the chain and the nature of the monomers. For example, polyvinyl alcohol has numerous polar sites so it’s very water soluble, but polystyrene is made of many styrene units, which are benzene rings and are very nonpolar so it doesn’t dissolve in water. Plastics are also different because of the way they are manufactured. For example, plastic foam cups keep beverages hot or cold well because they are made of polystyrene that has been pumped full of air. The dead air space acts as a good insulator. However, plastic forks are also made of polystyrene but with no added air so they are a higher density and would not be good insulators.