Influence of 60Co γ-ray irradiation on the morphology of crystalline polyethylene studied by high-resolution solid-state 13C NMR

The relationship and influence of varying 60Co γ-ray irradiation doses, in the range 0.77-5.2 MGy, on the morphology of polyethylene have been investigated using high-resolution solid-state 13C nuclear magnetic resonance analyses through variation of different phase components, T1c, T2c relaxation parameters, and line width. The cross-linking in the irradiated polyethylene takes place mainly in the non-crystalline regions. However, distortion and damage to the folded chain of the crystal lattice are observed in the crystalline regions. For the interfacial phase, both cross-linking and distortion could occur. As a result, part of the crystalline component transformed into a non-crystalline one. It was also found that the orthorhombic crystalline lattice transformed into a monoclinic one within the crystalline phase in polyethylene under higher doses of irradiation. (author)