A prepreg comprising: a fiber reinforcement; and a curable resin which comprises: 25 to 35 weight percent tetrafunctional epoxy resin based on the total weight of the curable resin; 18 to 28 weight percent difunctional epoxy resin based on the total weight of the curable resin; 4 to 18 weight percent polyether sulfone based on the total weight of the curable resin; 2 to 10 weight percent polyamide 12 particles based on the total weight of the curable resin; 2 to 10 weight percent polyamide 11 particles based on the total weight of the curable resin; 1 to 8 weight percent potato shaped graphite particles based on the total weight of the curable resin; and 17.4 to 27.4 weight percent of a curing agent for said curable resin based on the total weight of the curable resin.