CONFORMATION-SENSITIVE ABSORPTION-BANDS IN THE IR-SPECTRA OF POLYACRYLONITRILE SUBJECTED TO LASER TREATMENT, THERMAL-SHOCK, AND GAMMA-IRRADIATION

The effect of laser treatment, thermal-shock, and gamma-irradiation on the structure of polyacrylonitrile (PAN) is studied by IR spectroscop y. It is demonstrated that the IR absorption bands observed in the ran ge from 900 to 1120 cm-1 are conformation-sensitive. A detailed analys is is made of the behavior of the absorption band at 960 - 970 cm-1. I t is found that the above treatments, as well as subsequent heat treat ment, strongly affect the position and intensity of the band. The obse rved spectral changes in the range from 900 to 1120 cm-1 involve a shi ft of the band at 1360 cm-1 to shorter wavelengths, which indicates th e appearance of more planar fragments in the polymer chains.