Manufacture of prepreg compositions, and determination of their suitability for use in composite structures

A method of determining a suitability of a prepreg composition for incorporation into a composite structure, comprising:

• illuminating the prepreg composition with light of a first wavelength, wherein the prepreg composition comprises:
• a bed of fibers disposed in a partially cured resin matrix;
• and
• a plurality of core/shell quantum dots disposed on or in the resin matrix, each quantum dot including an inner core covered by an outer shell;
• the inner core being such that when excited by light of the first wavelength the inner core emits a detectable luminescent signal at a second wavelength;
• the outer shell being such that it blocks light of the first wavelength from reaching the inner core when the outer shell is intact;
• and
• the outer shell further being such that it degrades upon exposure to UV radiation such that a detection of the luminescent signal at the second wavelength indicates that the quantum dot has been exposed to UV radiation;
• detecting the luminescent signal at the second wavelength from the inner core;
• and
• determining a suitability of the prepreg composition for incorporation in a composite structure based upon at least the presence of the detected luminescent signal at the second wavelength.

A method of detecting damage to a prepreg composition due to UV radiation exposure, comprising:

• a) forming a bed of fibers;
• b) contacting the fiber bed with a resin matrix;
• c) disposing a plurality of core/shell quantum dots on or in the resin matrix to form the prepreg composition, wherein:
• each quantum dot includes an inner core covered by an outer shell;
• the inner core is such that when excited by light of a first wavelength the inner core emits a detectable luminescent signal at a second wavelength;
• the outer shell is such that it blocks light of the first wavelength from reaching the inner core when the outer shell is intact;
• and
• the outer shell is such that it degrades upon exposure to UV radiation such that a detection of the luminescent signal at the second wavelength indicates that the quantum dot has been exposed to UV radiation;
• and
• d) detecting the detectable luminescent signal from the plurality of core/shell quantum dots after exposure to an amount of UV radiation sufficient to render the prepreg composition unsuitable for use in fabricating composite structures.