Chevron morphology in deformed semicrystalline polymers

Abstract

Chevron morphology was observed using transmission electron microscopy in various semicrystalline polymers deformed in tensile experiments. The morphological and mechanical prerequisites for chevron structure formation in semicrystalline polymers were revealed. It was demonstrated that chevron folding is a common deformation mode which can appear in real, i.e. globally unoriented or partially oriented samples, in areas where the lamellar stacks are oriented perpendicular to the deformation direction. Similarities with the behaviour of other layered systems were found. The mechanism of chevron formation is discussed in the light of the fundamental statements of the folding theories and is related to the specific microstructure of the polymers. The effect of boundary conditions, deformation temperature and macroscopic strain on the characteristics of the chevron structure is described.

Acknowledgements

The authors are indebted to Ing. S. Goerlitz and Ing. I. Naumann for a significant part of the TEM investigations presented in this work.