Precraze domains

Scheme (b) in Fig. 1.6 shows the transition from the precraze into the fibrillated craze in two directions the A direction from above and the B direction in cross section. An increase of the applied load P causes additional strain in the precraze domains, rupture of individual overstressed chain segments, and fibrillation of the polymer strands between the voids, transforming the structure of individual domains and nanovoids (a closed-cell structure) into the structure of fibrils and interconnected voids (an open-cell structure). The average distance of fibrils is, therefore, correlated to the distance between domains of the craze nuclei in the precraze and, consequently, to the mesh distance of the entanglement network in Fig. 1.2. 

Step 2 with increasing load, the precrazes of the micrograph (a) (step 1) are transformed into fibrillar crazes by the mechanism of stretching domains, transforming into nanovoids, with stress concentration at the nanovoids and plastic deformation of the polymer material between the nanovoids up to fibrillation (see Fig, 1,6) ... 

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