| Abstract: | In order to ascertain whether the crystal core of irradiated polyethylene single crystals is free from crosslinks—as would follow from the results of Part I—the fold surface of irradiated single crystals was shaved off with ozone and the resulting product examined by GPC for molecular weight. It was found that on ozone degradation the entire material, which had been insolubilized by radiation-induced crosslinking, has become soluble hence became available for the GPC analysis. The chromatograms displayed the same peaked development with degradation as the unirradiated crystals leading eventually to single traverse dicarboxylic acids. This proves the absence of crosslinks within the crystal interior of the material as examined by GPC. The appearance of some additional low molecular weight material, is attributed to scission at the radiation-induced double bonds due to ozone which eliminates the possibility of the existence of crosslinks within the lattice such as might provide scission sites for ozone. The conclusion could therefore be reached that, to the extent assessable by our GPC test, there are no radiation-induced crosslinks within the crystal lattice, hence the crosslinks produced must be entirely confined to the fold surface region of the crystals. |
