Effect of carbonaceous nanofillers and triblock copolymers on the toughness of epoxy resin
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Effect of carbonaceous nanofillers and triblock copolymers on the toughness of epoxy resin Alessandra Lavoratti1 · Ademir José Zattera2 · Sandro Campos Amico1 Received: 29 May 2019 / Revised: 26 August 2020 / Accepted: 23 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The toughening of epoxy resins is a relatively recent trend in composite technology. The use of rigid carbonaceous fillers or plasticizing additives is well established in the literature, but their combined use and their effect on thermal or mechanical properties of composites is hardly studied. The aim of this work is to investigate the combination of neat and silane-treated carbonaceous fillers (graphene oxide (GO) or graphite nanoplatelets (GNP)) with poly(ethylene oxide)-poly(propylene oxide)poly(ethylene oxide) (EPE) triblock copolymers. The viscosity and curing behavior of the resin, as well as the dynamic mechanical and mechanical properties of the composites, were evaluated. Addition of EPE and GO slightly increased viscosity of the epoxy resin, and EPE acted as coupling and exfoliating agent of GO and GNP. EPE/GO-modified epoxy showed the lowest storage modulus and cross-link density, displaying in turn a more pronounced effect on impact strength and fracture toughness without sacrificing tensile and thermal properties. Treatment with APTES did not cause a significant effect on the composite properties. Keywords Triblock copolymer · Graphene oxide · Graphite nanoplatelets · Silanes · Epoxy resin · Composites
* Alessandra Lavoratti [email protected] 1
Postgraduate Program in Mining, Metallurgical and Materials Engineering (PPGE3M), Universidade Federal Do Rio Grande Do Sul (UFRGS), Av. Bento Gonçalves, 9500, Porto Alegre, RS 91501‑970, Brazil
2
Postgraduate Program in Engineering of Processes and Technologies (PGEPROTEC), Universidade de Caxias Do Sul (UCS), Rua Francisco Getúlio Vargas, 1130, Caxias Do Sul, RS 95070‑560, Brazil
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Polymer Bulletin
Introduction Toughening epoxy resins is a relatively recent and growing trend. Their brittle nature, due to their highly cross-linked network, can be improved by adding micro- or nanofillers. Carbonaceous nanofillers such as graphene oxide (GO) have been successfully used as toughening agents for epoxies while also increasing tensile strength and thermal stability due to the GO highly functionalized surface with hydroxyl, carbonyl carboxyl and epoxy groups, which may be compatible with epoxy resins and silane coupling agents. Moreover, the increase in interlayer spacing due to the GO functionalities can yield better exfoliation and thus higher tensile strength and stiffness [1, 2]. Lately, graphite nanoplatelets (GNP) have emerged as an alternative to GO due to their lower cost and higher aspect ratio in comparison with other carbonaceous fillers, providing some degree of toughening without increasing viscosity of the resins [3, 4]. And while some authors report an increase in plane-strain fracture toughness and impact stren
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