Composite materials

A structural preform adapted for resin infusion, said structural preform comprising:

• multiple layers of reinforcing fibres that are not impregnated with resin;
• and
• at least one nonwoven veil comprised of conductive polymeric fibres arranged randomly,
• wherein the conductive polymeric fibres are formed from a blend of a conductive material and a polymeric material, and the polymeric material comprises one or more polymers that are initially in a solid phase and are substantially insoluble in a curable resin composition to be introduced into the preform by resin infusion, but is able to undergo at least partial phase transition to a fluid phase during a cure cycle of the resin-infused preform.