Polymer vs Plastic

What is a polymer? What are plastics?

Here is a simple explanation of the difference between polymers and plastics.

All plastics are polymers, but not all polymers are plastic. Plastic is a specific type of polymer. Plastics are synthetic and do not occur naturally.

With this in mind, we can dig a little deeper into the definitions.

What are polymers?

Polymers can be either natural or synthetic and are created when small molecules, also known as monomers, combine chemically to form a larger network of connected molecules. The term is derived from the Greek prefix “poly-,” which means “many,” and the suffix “-mer,” which means “parts.”

What makes these networks unique is the fact each polymer creates a network of repeating units. For example, a repeating unit in the chemical structure of natural rubber is isoprene. In the image below, you can see repeating units of isoprene after isoprene is turned into a natural rubber.

The chemical structure of natural rubber. Notice repeating units of isoprene.

The repeating units in polymers are often carbon and hydrogen and sometimes oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorus and silicon.

Examples of natural polymers:

  • Rubber
  • Wool
  • Protein
  • Cotton
  • DNA (deoxyribonucleic acid)

In fact, all life forms are made up of some combination of naturally occurring polymers.

What are plastics?

Plastics are a specific type of synthetic polymer with a large molecular mass where the structure is mostly linear – they resemble spaghetti with long chains. The first synthetic plastic was created in 1909 for telephone and electrical components and was known as Bakelite.

Manufactured polymers are called thermoset polymers when they are three-dimensional networks that do not melt once formed. An example would be an epoxy resin used in two-part adhesives.

Manufactured polymers are called thermoplastic polymers when they are one-dimensional chains that can be melted. The majority of manufactured polymers are thermoplastic, meaning they can be heated and reformed over and over again. This is the property that allows them to be recycled and reused.

Examples of synthetic thermoplastic polymers:

  • PET (polyester) bottle / water bottle
  • PE (polyethylene) film / plastic bags
  • PS (polystyrene) cup / foam cup
This is polyethylene in pellet form. Molecularly, PE consists of 2 carbon atoms with 1 hydrogen atom.

Each type of polymer has a very distinct characteristic, but here are some general attributes:

  1. Resistant to chemicals
  2. Thermal and electrical insulators
  3. Lightweight and strong
  4. Multiple process methods including extrusion, injection molded, blowmolded, etc.
  5. Petroleum based (typically but not always)
  6. Diverse and unique applications – plastics have changed the way we live, from medicine to automobiles to our homes

While plastics have found an important role in our lives, there are several downsides:

  1. Made from nonrenewable crude oil resources
  2. Give off toxic fumes when burned
  3. Non-recyclable materials are difficult to re-purpose and do not decompose in landfills

To combat the end-of-use dilemma with this durable material, RSP uses a number of environmentally friendlier techniques. We incorporate recycled and reclaimed plastics from the ocean and use additives such as natural fibers from hemp and rice, as well as natural substances that help plastics biodegrade in landfills.

If you have additional questions or want to learn more about choosing the right material for your product, please call our sales team!