36 A. B. Irez et al. Table 4.4 Comparison of mechanical properties of GAC specimens Flexural stress (MPa) Flexural modulus (MPa) Strain in break (ε %) KIc (MPam1/2) GIc (kJ/m2) GAC I 14.70 ±1.85 933 ±264 0.38 ±0.076 0.38 ±0.01 0.154 ±0.01 GAC II 15.40 ±3.16 972 ±269 0.39 ±0.06 0.39 ±0.02 0.158 ±0.016 GAC III 15.40 ±4.29 957 ±257 0.37 ±0.02 0.54 ±0.08 0.312 ±0.1 Fig. 4.3 Fracture surfaces after 3 PB testing (a)GAC I (b)GAC II (c)GAC III After the realization of bending tests, fracture surfaces were observed by means of scanning electron microscopy (SEM). Fracture surfaces obtained from 3 PB tests have been analyzed by means of Scanning Electron Microscopy (SEM). It noticed that good adhesion of the both of the reinforcements in the rubber based matrix by creating an ideal interface for each composition, as presented in Fig. 4.3 with different fracture surfaces taken by SEM. Cavitation and void formation in the rubber matrix with matrix expansion and locally, debonding of nano particles with consequent void growth can be identified in the structure as the improved toughening mechanisms. For this evolution, the mixture of devulcanized rubber (85 wt %) with epoxy (15 wt %) plays an important role. Some of the specimens with homogenous distribution of the nanoparticles have shown a typical debonding of the fine particles. This phenomena can
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