PSI - Issue 10

G.V. Seretis et al. / Procedia Structural Integrity 10 (2018) 249–256 G.V. Seretis et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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As regards the tensile strain, it seems to be affected by the GNPs content increase similarly to the T2×2 fabric reinforced specimens. After an initial slight tensile strain drop, strain at break increases while GNPs content increases up to 4% w.t. The constantly increasing inter-yarn friction, while increasing the GNPs content, leads to a subsequent increase in tensile strain. However, since there are much lower inter-yarn interactions for this kind of fabric, the increase rate is considerably lower as compared with the T2×2 fabric reinforced specimens. Further increase in GNPs content, which causes an even greater frictional inter-yarn interaction, leads to a significant strain at break decrease, indicating an early collapse of the fibrils.

Fig. 10. Strain at break for all GNPs contents of UD specimens. The average strain at break value for each GNPs content is noted on the graph. 4. Conclusions Graphene nanoplatelets (GNPs) reinforced glass fabric/epoxy nanocomposite laminae of different GNPs contents were produced using two different E-glass fabric types. The produced nanocomposite specimens were investigated as per their tensile performance and examined using a scanning electron microscope (SEM) and an atomic force microscope (AFM). Based on the experimental observations the following general remarks may be drawn: (a) The AFM measured height distribution before and after the peak that corresponds to a GNP is described by a constant height profile, indicating that no voids were found at the GNPs boundaries. Therefore, the embodiment of the GNPs in the epoxy matrix was proper. (b) As can be observed in the 3D micrographs, into a fiber, the GNPs are located on the fibrils ’ surfaces and not in the inter-fibril regions. (c) For the specimens reinforced with both types of E-glass fabric, i.e. Uni- Directional and Twill 2×2, a considerable increase in Ultimate Tensile Strength (UTS) can be observed for w.t. GNPs contents up to 1%. For further increase of the GNPs content, the UTS progressively decreases. This indicates a progressively increased inter-yarn friction while GNPs content increases. However, this progressively increasing inter yarn frictional behavior positively affects the tensile strain. (d) For the Uni-Directional fabric reinforced specimens, since there are much lower inter-yarn interactions for this kind of fabric due to the considerably lower number of weaving nodes in this case, the tensile strain increase rate was considerably lower as compared with the Twill 2×2 fabric reinforced specimens. (e) For the same reason, i.e. due to the lower number of weaving nodes and therefore of inter-yarn interactions, the UTS reduction rate while increasing the GNPs content is quite lower for Uni-Directional fabric reinforced specimens. References Chu, K., Li, W., Dong, H., 2012. Role of graphene waviness on the thermal conductivity of graphene composites. Applied Physics A 111, 221-225. Colangelo, F., Russo, P., Cimino, F., Cioffi, R., Farina, I., Fraternali, F., Feo, L., 2017. Epoxy/glass fibres composites for civil applications: Comparison between thermal and microwave crosslinking routes. Composites Part B: Engineering 126, 100-107. Dai, X., Zhang, Z., Chen, C., Ding, Q., Li, M., Mai, K., 2017. Mechanical properties improvement of montmorillonite-filled isotactic polypropylene nanocomposites by β -modification. Polymer Composites 38(S1), E412-E420.