Some Aspects of the Lattice Destruction of Polyethylene Due to Electron Irradiation

When n-C28H58 is exposed to electron beams, the (200) and (110) spacings remain constant in-dependently of irradiation dose, and for the longer paraffins, these spacings increase with the dose. The longer the molecules, the more remarkable their dose dependence is. Polyethylenes are more easily subjected to electron radiation damage than n-C94H199, although the length of stem segments of both crystals is the same. The difference is caused by that of the crystalline state between them; polyethylene crystals are composed of folded chains, while molecules are extended in n-C94H194. The fact that the irradiation behavior depends on the molecular length is interpreted in terms of molecular mobility within the crystal lattice. Since in the case of paraffins with small length, molecules are very mobile, the lattice strain imposed by electron irradiation is relaxed and apparently the lattice spacings are less dependent on the irradiation dose. Further, the mechanism of lattice destruction of polyethy-lene is examined using the optical transform method; model lattices are set up and its optical trans-forms are compared with the electron diffraction patterns. It is found that the cross-link model pro-posed by Nagasawa and Kobayashi s not suitable as it is