Heyer, D. (Corresponding author)FZJ*

1981
Kernforschungsanlage Jülich, Zentralbibliothek, Verlag Jülich

Report No.: Juel-1723

Abstract: This work reports the first direct determination of the microscopic elastic shear constants C$_{44}$ , C$_{55}$, C$_{66}$ and C' = $\frac{1}{4}$(C$_{11}$+C$_{22}$-2C$_{12}$ ) of crystalline polyethylene at room temperature. Fully deuterated and uniaxially oriented polycrystalline sampIes were used. The constants were obtained from a comparison of inelastic neutron scattering intensity profiles at low energy transfer near Bragg reflections with calculations in the long wavelength limit. The results are C44 = 2.1 $\pm$ 0.3 GPa, C$_{55}$ = 2.2 $\pm$ 0.3 GPa, C$_{66}$ = 1.46 $\pm$ 0.25 GPa and C' = 0.87 $\pm$ 0.25 GPa. Earlier macroscopic data can be derived satisfactorily from the measured constants assuming homogeneous stress in the sample.

1. Institut für Festkörperforschung (IFF)