Abstract: The effects of UV irradiation on high cis-1,4-polybutadiene (NiBR) were studied by 1D and 2D NMR spectroscopy, ¹H relaxation time measurements and X-ray diffraction. The results indicated that, with the increase of UV irradiation time, oxidation reaction takes place more often in the side vinyl group terminated of polybutadiene than in the double bonds terminated in the main chain. Moreover, the increase of the halfwidth of the peaks upon irradiation indicated that the crosslinking reaction had occurred. The X-ray diffraction data showed that the intensity of the crystallization peak decreased with the increase of UV irradiation time. This indicated that the crystal content of the sample was reduced by UV irradiation. The changes in ¹H relaxation times provided important insight into the effects of irradiation on molecular segmental motion in the polymer.

Key words: NMR, NiBR, X-ray diffraction, irradiation effects