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Article

Cyclic Olefin Copolymer Interleaves for Thermally Mendable Carbon/Epoxy Laminates

1
Department of Industrial Engineering, University of Trento, 38123 Trento, Italy
2
National Interuniversity Consortium of Materials Science and Technology (INSTM), 50121 Florence, Italy
*
Authors to whom correspondence should be addressed.
Academic Editors: Giulio Malucelli and Hom Nath Dhakal
Molecules 2020, 25(22), 5347; https://doi.org/10.3390/molecules25225347
Received: 27 October 2020 / Revised: 12 November 2020 / Accepted: 13 November 2020 / Published: 16 November 2020
(This article belongs to the Special Issue Preparation, Characterization and Applications of Polymer Composites)
Thin cyclic olefin copolymer (COC) foils were used as intrinsic thermoplastic healing agents in carbon fiber (CF)-reinforced epoxy laminates. COC films were produced by hot pressing and were interleaved in the interlaminar regions between each EP/CF lamina, during the hand layup fabrication of the laminates. Three samples were produced, i.e., the neat EP/CF laminate without COC, and two laminates containing COC layers with a thickness of 44 μm and 77 μm, respectively. It was observed that the fiber volume fraction decreased, and the porosity increased with the introduction of COC layers, and this effect was more evident when thick films were used. These two effects, combined with the sub-optimal adhesion between COC and EP, caused a decrease in the mechanical properties (i.e., the elastic modulus, flexural strength, interlaminar shear strength and interlaminar fracture toughness) of the laminates. Specimens subjected to mode I interlaminar fracture toughness test were then thermally mended under pressure by resistive heating, through the Joule effect of conductive CFs. A temperature of approximately 190 °C was reached during the healing treatment. The healing efficiency was evaluated as the ratio of critical strain energy release rate (GIC) of the healed and virgin specimens. Healed specimens containing COC layers of 44 μm and 77 μm exhibited a healing efficiency of 164% and 100%, respectively. As expected, the healing treatment was not beneficial for the neat EP/CF laminate without COC, which experienced a healing efficiency of only 2%. This result proved the efficacy of COC layers as a healing agent for EP/CF laminates, and the effectiveness of resistive heating as a way to activate the intrinsic healing mechanism. View Full-Text
Keywords: thermal mending; self-healing; cyclic olefin copolymer; laminates; carbon fiber; epoxy thermal mending; self-healing; cyclic olefin copolymer; laminates; carbon fiber; epoxy
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MDPI and ACS Style

Zovi, R.C.; Mahmood, H.; Dorigato, A.; Fredi, G.; Pegoretti, A. Cyclic Olefin Copolymer Interleaves for Thermally Mendable Carbon/Epoxy Laminates. Molecules 2020, 25, 5347. https://doi.org/10.3390/molecules25225347

AMA Style

Zovi RC, Mahmood H, Dorigato A, Fredi G, Pegoretti A. Cyclic Olefin Copolymer Interleaves for Thermally Mendable Carbon/Epoxy Laminates. Molecules. 2020; 25(22):5347. https://doi.org/10.3390/molecules25225347

Chicago/Turabian Style

Zovi, Riccardo C., Haroon Mahmood, Andrea Dorigato, Giulia Fredi, and Alessandro Pegoretti. 2020. "Cyclic Olefin Copolymer Interleaves for Thermally Mendable Carbon/Epoxy Laminates" Molecules 25, no. 22: 5347. https://doi.org/10.3390/molecules25225347

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