Raman characterization
Fig. 7 is Raman spectra of modified PVDF membranes with different
reaction time. As shown in Fig. 7, the characteristic conjugate
vibration peak of C@C was not nearly observed at 1 min of
reaction time, which indicated that the formed double bond contents
were less at the reaction beginning. However, at 5 min the
vibration peak of C@C emerged at 1600 cm1 obviously and interactional
vibration peaks between CAC and C@C at 1300 cm1 were
prominent, which proved that the double bonds were generated
due to the reaction. Moreover, all those peaks mentioned above turned weaker afterward. The conclusion drawn from Fig. 7 was
in consistent with the results in Figs. 5 and 6 [22,25].