Direct application of thermosetting composite surfacing films to uv-treated thermoplastic surfaces and related composite structures

A method of preparing a direct-bonded thermoplastic-thermoset composite, the method comprising:

• (a) irradiating a surface of a thermoplastic substrate with actinic radiation sufficient to activate the surface of the thermoplastic substrate;
• (b) contacting a thermosetting or thermosettable surfacing film to the activated thermoplastic substrate surface;
• and
• (c) applying pressure, and optionally heat, to the thermosetting or thermosettable surfacing film against the thermoplastic substrate for a time and under conditions sufficient to form a direct bond between the thermoplastic substrate and the thermosetting or thermosettable surfacing film.