NMR and cured plastics

Please forgive me for my ignorance but my studies with regards to NMR was lifetimes ago! I work with Polyurethane systems and my question with regards to these is the following: If the polyurethane material is cured out (like a hard plastic like PE or ABS rigid) would there be any detectable signal in a NMR test and/or in a MRI instrument? My thought is that as long as the polyurethane is 100% reactive it is solid and kind of in a pseudo frozen state, a state in which the electrons are not readily manipulated by the magnetic field for alignment as well as less susceptible for RF deflection. I could imagine that if a unreactive material is used like a plasticizer it will be distributed as a liquid and make it available for alignment and flipping which would allow for detection. Thank you for your thoughts on this topics and please know your assistance is greatly appreciated.

Best Regards