A composite material can be defined as a mixture of two or more mechanically separable materials that when combined give properties superior to the properties of the individual components.

 

Key terms within this definition are:

 

‘Mixture’ - in chemistry terms this refers to substances that are combined but not through a chemical reaction.

 

‘Mechanically Separable’ – this reinforces the term ‘mixture’ but in reality can be difficult to achieve. This is the major obstacle that can make composite materials difficult to recycle.

 

‘Properties superior to the individual components’ – this indicates that the mixed materials are working together and not individually. Combined they now have better properties.

Constituent parts of a composite

 

Reinforcement
The role of the ‘reinforcement’ is to fortify the matrix in terms of strength and stiffness.

 

Matrix
The ‘matrix’ has three roles.

• To support the reinforcement and to keep the reinforcement in its correct orientation.
• To bond the reinforcement so that applied loads can be effectively transferred to the reinforcement.
• To protect the reinforcement from chemical and environmental attack.