ABSTRACT
Let us briefly consider some concepts concerning lifetime and strength of polymers as well as some specific features of elementary fracture events and kinetics of fracture at macroscopic level. In this chapter, we will also discuss the newly published literature on strength and fracture of solids, and this discussion involves some physical fundamentals of the temperature-time dependences of strength and the further development of the theoretical speculations concerning the temperature-time dependence of strength in polymers. In this chapter, a special attention is addressed to the principal results of the mathematical theory of cracks which are very important for the further development of the theoretical speculations concerning the kinetics of polymer fracture in terms of the ideological scheme (6). This chapter will also consider surface and inner cracks (rectilinear and circular, disklike) as detected in polymer films and fibers by diffraction methods. In addition to the mechanical stress, the case of thermal stress (in addition to mechanical stress and without it) will be described which offers and this offers new aspects of physics and mechanics of polymers. The results presented in this chapter are used to derive several relationships of time dependence of strength of polymers which are widely applied for the treatment of strength and lifetime spectra.
