ABSTRACT

I. Introduction ................................................................. 160 II. Cavitation during Plastic Deformation of

Polymers....................................................................... 164 III. Deformation Mechanisms in Crystalline

Polymers....................................................................... 170 IV. Plasticity of Polymer Crystals.................................... 179 V. Strength of Crystalline Polymers............................... 185 VI. Cavity-Free Deformation ............................................ 192

VII. Rolling with Side Constraints .................................... 194 A. Case of Isotactic Polypropylene (iPP) ............. 196 B. Case of High-Density Polyethylene

(HDPE) .............................................................. 199 VIII. Conclusions .................................................................. 200 Acknowledgments................................................................. 202 References............................................................................. 203

I. INTRODUCTION

The definitions of strength and toughness are well established in the mechanics of materials. The basic dependencies for the strength and toughness of polymers were discussed by Young [1] in an older review. Crystalline polymers, which are the object of this report, are complicated systems, with an amorphous phase interlaying with crystalline lamellae, and with most of the macromolecular chains engaged in both phases. The strength and toughness of polymer crystalline systems are interdependent, due to several affecting phenomena such as crystal plasticity, cavitation and molecular orientation.