Dislocations in polyethylene crystals: line energies and deformation modes

Publisher Website
Google Scholar
Abstract
Explicit expressions are obtained for the line energy of straight dislocations in orthorhombic polyethylene crystals. It is found that the ⟨0, 0, c⟩ screw dislocation is the perfect dislocation with the lowest line energy whilst the ⟨0, 0, c⟩ edge has negative line tension and is therefore unstable. The possible dissociation of perfect dislocations into partials is discussed, and it is shown that both (110) and (310) twin dislocations can arise from such dissociations. Numerical calculations also show that homogeneous nucleation of ⟨0, 0, c⟩ dislocations, and twin dislocations, has a very high probability of occurrence under a stress of the order of the yield stress of polyethylene crystals. These results help to explain the readiness of polyethylene crystals to deform by c axis slip, twinning, and monoclinic transformation modes. The supression of c axis slip by irradiation and cross-linking is also explained by the very high line tension of the ⟨0, 0, c⟩ screw dislocations.

This publication has 20 references indexed in Scilit: