Fracture viscoelastic rupture

This approach assumes that there is a region surrounding the crack tip with local energy dissipation. This arises from viscoelasticity, plasticity and bond rupture and can be considered the characteristic of the fracture process. For polymers the characteristic of this localized energy dissipation is considered to be independent of geometries. 

Bueche and Halpin 126, 203, 215-217) have developed a fracture theory for amorphous rubbers. Their model pictures rupture as the result of the propagation of tears or cracks within the material. The growth of a tear is viewed as a process in which molecular chains at the tip of the tear stretch viscoelastically, under the influence of a high stress concentration, until they rupture. The failure process is a non-equilibrium one, developing with time and involving consecutive rupture of molecular chains. The principal result of the theory is embodied in the equation... 

Energy loss through viscoelastic dissipation usually contributes to the fracture energy of an adhesive bond sometimes that contribution is dominant. Adhesives are often designed to operate in the regions where viscoelastic losses (tan 5) are high. Further discussion can be found under Adhesion - fundamental and practical. Peel tests and Tensile tests see also Creep and Durability creep rupture. 

Lakes, R. S., Viscoelastic solids, CRC Press, Boca Raton, FL, (1998). Landel, R.F., and Fedders, R.F., Rupture of Amorphous Unfilled Polymers , in Fracture Processes in Polymeric Solids (B. Rosen, ed.),... 

Some of the papers referenced do this for rubber, nylon and tooth dentins. Peterlin, Zhurkov et al. and Becht have also made quantitative measures of bond rupture. In answer to your second question, our experimental evidence (J. Polym. Sci. A-1, 7, 2125 (1969) indicates only a small fraction of the total work of fracture can be attributed to primary bond rupture. The remainder may be attributed to secondary bond rupture, plastic and viscoelastic deformation somewhat analogous to work of plastic deformation at the tip of a crack in metals. 

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