Polyester resin

These are liquids with the polyester usually dissolved in styrene to reduce its viscosity for ease of fabrication. A catalyst such as organic peroxide is added to produce polymerization (solidification) with the application of heat around 100°C to 160°C. The materials show considerable mould shrinkage unless a thermoplastic additive is used to reduce this.

This is a very widely used matrix material, generally in conjunction with glass fibre reinforcement. Use is mainly restricted to lower performance applications. Bonding between the matrix and the glass fibre is strong, provided a silane coupling agent is used. Other types of reinforcement fibre are generally not used because of inadequate bonding to the resin.