Branching and degradation of high-molecular-weight polyethylene

The effect of γ-radiation on the molecular weight distribution and structure of high-molecular-weight polyethylene was studied with doses below the gelation level by measuring the sedimentation coefficients and molecular weights of samples before and after irradiation. The mean number of branch points per chain was calculated from the ratio of sedimentation coefficients. The number of elementary degradation and crosslinking reaction steps as well as the number of branch points per macromolecule were determined. The statistical theory used in the calculations was found to be appropriate for describing the branching and degradation of high-molecular-weight PE.