On the Terminology and Structural Interpretation of Stress‐Strain Curves During Uniaxial Stretching of Soft‐Chain Semicrystalline Polymers

On the basis of the literature and, in particular, the author's (BMG) experimental data about the shear deformation of low density polyethylene (LDPE), as a typical, widely used, soft‐chain amorphous‐crystalline polymer, a correlation of different parts of the most typical stress‐strain curve during uniaxial stretching, on the one hand, and corresponding structural changes, on the other, was carried out. Interpretation of different stages of deformation in terms of a shear deformation of crystallites is given; the various phenomena accompanying the deformation process, in particular, a neck formation, are discussed. The analogy of deformation curves and van der Waals isotherms for the vapor‐liquid transition is discussed. The analogy allows the explanation of a wide spectrum of experimental data that has been reported by various authors studying the deformation of oriented and nonoriented samples of semicrystalline polymers under various conditions. On the basis of the developed concepts we also speculate about the origin of deposits of minerals, in particular metals, in the Earth's crust.

Keywords:

• semicrystalline polymers
• stress‐strain curves
• supermolecular structure

Acknowledgments

This work was carried out with financial support (for BMG) within the framework of the Program OE‐13 of fundamental researches of the Russian Academy of Sciences. Experimental studies by PHG, et al. were primarily carried out with support of various grants from the U.S. National Science Foundation Polymer Program