A process for curing a prepreg, comprising the steps of Providing a prepreg comprising a thermosetting resin composition and fiber; Placing the prepreg under reduced pressure Exposing the prepreg under reduced pressure to a first elevated temperature for a time sufficient to: remove volatile materials in the prepreg in an amount defined below, and increase viscosity of the prepreg to a range of 0.1 to 4000 Pa·s (1 to 40,000 Poise); Optionally, exposing the prepreg under reduced pressure to a second elevated temperature for a time sufficient to remove any remaining volatile materials in the prepreg; Exposing the prepreg under reduced pressure to a third elevated temperature for a time sufficient to cure the prepreg; and Exposing the cured prepreg to a fourth elevated temperature condition that is less than any one or more of the first, second or third elevated temperature conditions with or without reduced pressure, Characterized in that in the step of exposing the prepreg under reduced pressure to a first elevated temperature, the amount of volatile materials removed is 1% by weight to 3% by weight based on the total weight of the prepreg; and the thermosetting resin comprises a benzoxazine selected from Providing a prepreg comprising a thermosetting resin composition and fiber; Placing the prepreg under reduced pressure Exposing the prepreg under reduced pressure to a first elevated temperature for a time sufficient to: remove volatile materials in the prepreg in an amount defined below, and increase viscosity of the prepreg to a range of 0.1 to 4000 Pa·s (1 to 40,000 Poise); Optionally, exposing the prepreg under reduced pressure to a second elevated temperature for a time sufficient to remove any remaining volatile materials in the prepreg; Exposing the prepreg under reduced pressure to a third elevated temperature for a time sufficient to cure the prepreg; and Exposing the cured prepreg to a fourth elevated temperature condition that is less than any one or more of the first, second or third elevated temperature conditions with or without reduced pressure, Characterized in that in the step of exposing the prepreg under reduced pressure to a first elevated temperature, the amount of volatile materials removed is 1% by weight to 3% by weight based on the total weight of the prepreg; and the thermosetting resin comprises a benzoxazine selected from remove volatile materials in the prepreg in an amount defined below, and increase viscosity of the prepreg to a range of 0.1 to 4000 Pa·s (1 to 40,000 Poise); Optionally, exposing the prepreg under reduced pressure to a second elevated temperature for a time sufficient to remove any remaining volatile materials in the prepreg; Exposing the prepreg under reduced pressure to a third elevated temperature for a time sufficient to cure the prepreg; and Exposing the cured prepreg to a fourth elevated temperature condition that is less than any one or more of the first, second or third elevated temperature conditions with or without reduced pressure, Characterized in that in the step of exposing the prepreg under reduced pressure to a first elevated temperature, the amount of volatile materials removed is 1% by weight to 3% by weight based on the total weight of the prepreg; and the thermosetting resin comprises a benzoxazine selected from