PSI - Issue 10

G.V. Seretis et al. / Procedia Structural Integrity 10 (2018) 249–256

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G.V. Seretis et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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of a GNP using the above equipment is given in Fig.2. On the left of the figure, see Fig.1(a), a SEM micrograph showing a GNP in the epoxy matrix is provided. The marked region is also presented focused using AFM, see Fig.2(b),(c). In the AFM 3D micrographs, the multi-layer structure of a GNP can be easy observed. There are surfaces formed on different heights as indicated by the height bar on the right of the micrographs. The way GNPs were located into the fibers, i.e. between the fibrils, is shown in Figs.(3,4). In Fig.3 AFM micro graphs on the longitudinal section of a fiber of a nanocomposite lamina, after the application of a South-East Laplace gradient FIR filter, show GNPs on the fibrils' surface and between, together with the recorded height distribution. The height distribution corresponds to the region marked with a red square, i.e. the region around a GNP. Fig.4 shows a cross section of a fiber, in which a few fibrils and GNPs on their boundaries can be found. As can be observed in the 3D micrographs, the GNPs are located on the fibrils ’ surfaces and not within the inter-fibril regions.

Fig. 2. SEM micrograph showing a GNP in the epoxy matrix (a) and AFM micrographs showing details of its boundary (b,c).

Fig. 3. AFM micrographs showing GNPs on the fibrils' surface, after South East Laplace gradient FIR filter (longitudinal section), together with the recorded height distribution.

Fig. 4. AFM micrographs with smoothing filter applied showing GNPs on a fibril surface (cross section).

The GNPs embodiment in the epoxy matrix is presented in Figs.5 and 6. In Fig.5, GNPs can be observed in the matrix material, together with the linear height distribution of the line indicated with a red arrow, which includes a