ABSTRACT
I. Introduction ................................................................. 488 II. Toughening Principles and Mechanisms................... 489
A. Multiple Crazing............................................... 489 B. Multiple Shear Yielding ................................... 493 C. Intrinsic Brittle/Ductile Behavior ................... 496
D. Deformation and Fracture of Polymer Blends................................................................ 498 1. Multiple Shear Yielding in
Toughened Polymers ........................... 499 2. Effect of Rubber Concentration ......... 500 3. Role of Particle Size of the Rubber
Phase.................................................... 501 III. Toughening of Semicrystalline Polymers Using
Rubber and Rigid Fillers ............................................ 505 A. Thermoplastic Polyesters ................................. 506 B. Polyamides ........................................................ 517 C. Polyolefins ......................................................... 529
IV. General Conclusions and Future Outlook................. 535 Acknowledgments................................................................. 538 References............................................................................. 538
I. INTRODUCTION
The plastic deformation of polymeric materials can be grouped into two main mechanisms: crazing and shear yielding [1-3]. These two modes of deformation are controlled by the molecular characteristics of the polymers such as chain flexibility and chain entanglement density, and the testing conditions, including specimen geometry, deformation speed and test temperature. The type of specimen loading, for example tensile, flexural or compression loading, can also result in different deformation mechanisms. Among these parameters, under standardized testing conditions, the molecular characteristics of the polymer remain the prevailing parameter that directly or indirectly affects the deformation mechanism.
