2.5. 13C-NMRA super conducting magnetic resonance imaging apparatus (BrukerAVANCE 600, Switzerland) was used to detect the presence of FF andFG resins. The resonance frequency employed was 150 MHz. 300 μL ofsamples and 100 μL dimethyl sulfoxide (DMSO - d6) solvent were mixedand assessed. Test conditions: relaxation delay time was 6 s; scanningaccumulative number was 800–1200 times; and temperature of 25 °C