PSI - Issue 30

Aisen Kychkin et al. / Procedia Structural Integrity 30 (2020) 59–63 Aisen .Kychkin et al / Structural Integrity Procedia 00 (2020) 000–000

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3. Results and discussion For unfilled polymer (see Fig.1) the surface of fracture is homogeneous enough, and a crack, spreading, does not meet any serious delays. Fractographies of fracture surface of filled CNT of epoxy binder showed, that introduction of CNT substantially changes supramolecular structure, causes intensive gelation and forming of well-organized structures containing new formations of completely other quality, that is distinctly evident by the nature changes of surface of fracture of modified binders (see Fig.2).

Fig.1. Surface of the fracture of not modified epoxy binder: (a) increase x150; (b) increase x5000.

Fig. 2. Surface of the fracture modified epoxy binder containing CNT 0,10 mass%: (a) increase x150; (b) increase x5000.

The surface of the fracture of modified epoxy binder is distinguished by the presence of stages ("scales") of fracture that testify, that CNT form obstacle on the way of advancement of development front of structural damage. Expectantly increase of viscidity of fracture of the modified samples. In addition, CNTs is definitely (radially) orient the areas of binder, changing fracture of stress on the local areas. Cooperation of these stress fields at relatively even distribution of CNT in the binder form physical framework that can provide the increase of compression and bending strength. Thus tensile strength is decreasing. The results of tests are presented on Fig.3-5. The analysis of results of researches shows that within undertaken studies the degree of filling 0,10 mass% is optimally effective. In the vicinity of this area, there is a simultaneous growth of elastic- strength properties - tensile strength at compression, module of elasticity at compression and stress and impact strength. The tendency to decrease the tensile strength is understandable, CNT create steric restrictions and form a physical