A polymer is a compound made from different monomers. The properties of a polymer depend on the specific monomers it is made from and the conditions under which they are combined. As a result, different polymers have different properties. Also, the same polymer can have different properties if they are manufactured using different processes.

For example, poly(ethene) is a widely used polymer. Depending on the manufacturing process used, it can have different properties. This is why both low-density and high-density poly(ethene) can be produced, each with unique properties.

  • Low-density poly(ethene) (LDPE) is flexible, soft and lightweight. It is commonly used for bags, wraps and films
  • High-Density poly(ethene) (HDPE) is flexible, strong, durable and has a solid structure. It is typically used for toys, tanks, food preparation cutting boards and plumbing pipes.

The properties of a polymer can be changed by modifying the reaction temperature, reaction pressure and catalyst.

Types of Polymers

Polymers can be categorised into two types: thermosetting polymers and thermosoftening polymers.

Thermosetting Polymers

Thermosetting polymers have strong cross-links between monomers and different polymer chain, which hold the structure together. As a result, these polymers are strong, rigid, and do not soften when heated. They have high melting points and tend to char and burn rather than melt when exposed to heat.

Thermosoftening Polymers

Thermosoftening polymers do not have covalent bonds between polymer chains. This allows them to melt more easily than thermosetting plastics, which have covalent bonds between chains.

Thermosoftening polymers have low melting points. When heated, the intermolecular forces break, causing the polymer chains to separate and the polymer to melt. However, these polymers can be melted and remoulded into various shapes to create new products.