The classes of matrix material

The matrix material (usually referred to as the RESIN), is the binder which transfers the load to the reinforcement. It is also the first line of defence from environmental attack. It needs to be selected so that it can withstand the service temperature (high or low) conditions, and it should not be affected by fluids (gases or liquids) with which the composite will come into contact.

Many thermosetting and thermoplastic resins can be used for making composites but the selection of the material depends on cost, manufacturing capability, mechanical and environmental performance and availability.

For structural composites the most common thermoset resins include:

• Polyester resins
• Vinyl ester resins
• Epoxy resins

For high temperature or environmental resistance the most common thermosetting and thermoplastic resins include:

• Bismaleimide resins
• Polyimide resins
• Phenolic resins
• Polyetheretherketone (PEEK)
• Cyanate ester resins

For commodity or high volume products the resins are often thermoplastic and include

• Nylon e.g.6 or 6.6
• Polycarbonate
• Polyacetal
• Polyether imide
• Polyetheretherketone (PEEK)
• Polyphenylene sulphide
• Polyamide imide
  

Generally speaking, going down each of the lists above represents increasing cost, but increasing temperature and water resistance, coupled with higher impact strength and fracture resistance. The materials near the bottom of the list will usually only be used for 'high-end' applications.