Pls find attached FTIR of Polyacrylonitrile nanofiber before and after stabilization.

The sharp singlet at 2241 is the nitrile stretching mode of polyacrylonitrile, whereas the doublet around 2060 cm-1 is the gaseous phase of CO2 in the atmosphere unless you used nitrogen gas purge and perfectly balanced the state of purge between the reference and sample spectra. I assume the red spectrum is after thermally stabilized polyarylonitrile and thus the nitrile triple bonds are all converted into conjugated double bonds, which is reflected on the new, broad band around 1580-1600 cm-1.

@Hatsuo: sir. C triple bond N is successfully converted into C double bond N. But what peak at 2367 indicates?