ABSTRACT
This chapter discusses the molecular origins of toughness in polymeric systems. The mechanical properties of materials are of great importance in engineering applications. When a mechanical force is applied to a specimen, the deformation of the specimen is described in terms of its stress—strain behavior. The description of the mechanical properties of polymeric systems manifesting supramolecular organization is only at a molecular level when considering the properties of its components. There are significant differences between the small-strain and the large-strain behavior of polymers. Many types of polymeric systems manifest supramolecular organization, such as semicrystalline polymers, polymers filled with a particulate or fiber-reinforcing component, and blends, block copolymers, or graft copolymers of immiscible components. A major effort was made to account simultaneously for the temperature and the strain rate dependence of the yield stress. The determination of simple but reliable structure-property relationships for the crazing stress is another major challenge for future work.
