The energetics of kinks in polyethylene

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Abstract
The energetics of kinks in polyethylene have been investigated by means of conformational energy calculations on crystalline arrays of C14H30, C18H38, and C22H46. All of the parameters required for assessment of relaxation effects by site theory were calculated including the static defect energies, barriers to defect reorientation, and site strains. Up to two deformable coordination shells in the surrounding lattice were included. In the energy minimization calculations, all molecular internal degrees of freedom were allowed to participate. The effects of chain mismatch along the C axis at large distances from the defect were calculated from a continuum theory. The static defect energy is calculated to be 6.6 kcal/mole for C14H30, and the barrier for reorientation of right‐handed to left‐handed kinks is 10 kcal/mole. The barrier to “unkinking” to the nondefect state is 2 kcal/mole. The strain induced by the defect is largely a shear in the {0 0 1} plane in the 〈1 1 0〉 direction. It is concluded that although the barrier to reorientation is consistent with kink reorientation contributing to the γ process the predicted intensity rules out any but a very weak contribution to the total process.