The role of dislocations in γ-iPP under plastic deformation investigated by X-ray line profile analysis

Samples of γ-iPP were prepared by crystallization at elevated pressures using a specially designed pressure chamber. The γ-phase was subsequently investigated by dedicated in-situ X-ray diffraction experiments during deformation using synchrotron radiation. Parameters such as the crystallinity, the density of dislocations and the coherently scattering domain size (CSD-size) which in polymers corresponds to the lamella size, have been evaluated as a function of the strain by means of the multi-reflection X-ray line profile analysis (MXPA). Compared to the results for the α-phase, those for the γ-phase reveal an enhanced strength and a strongly reduced evolution of the dislocation density. The latter is explained in terms of a model comprising the formation of misfit dislocations.