The effects of carbon nanoparticles on curing kinetics of epoxy modified with triblock copolymer
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The effects of carbon nanoparticles on curing kinetics of epoxy modified with triblock copolymer Bruna Louise Silva1 · Marcia Bär Schuster1 · Roger Hoel Bello1 · Daniela Becker1 · Luiz Antonio Ferreira Coelho1 Received: 28 July 2020 / Revised: 16 October 2020 / Accepted: 1 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This work studies the effects of combining triblock copolymers with carbon nanoparticles (carbon nanotubes, graphene and carbon black) on curing kinetics. The chosen triblock copolymer was poly (propylene glycol)-block-poly (ethylene glycol)block-poly (propylene glycol) (PPG-b-PEG-b-PPG), which has different contents of PEG in its structure. The main objective is to investigate the influence of the miscibility of the PPG-b-PEG-b-PPG copolymer in epoxy nanocomposites. The PEG fraction in the copolymer structure was determinant for miscibility. The copolymer with the highest PEG fraction (50%) in its structure showed miscibility. The copolymer miscibility was critical for nanoparticle–matrix synergy, and the PPG-b-PEG-bPPG copolymer nanocomposite with 50 wt% PEG showed a greater increase in E’ in relation to the nanocomposite with PPG-b-PEG-b-PPG with 10% by weight of PEG. Cure kinetics results showed that the incorporation of carbon nanoparticles delays the kinetics as the temperature increases. Additionally, the miscible block copolymer delayed the curing reaction, whereas the immiscible one accelerated it, even with the addition of nanoparticles. Finally, DSC analysis allowed to verify that the cure kinetics of all studied copolymer nanocomposite systems satisfy Kamal’s autocatalytic model. Keywords Epoxy · Triblock copolymer · Cure kinetics
Introduction Epoxy resins have been widely used as a matrix in many composite-based automotive, aerospace and electronics applications and other industries. Such resins are thermosets with high thermal, chemical and mechanical resistance, making them the most used polymer matrix system. However, a highly cross-linked * Bruna Louise Silva bruna‑[email protected] 1
Santa Catarina State University - UDESC, Joinville, SC, Brazil
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Polymer Bulletin
microstructure makes unmodified epoxy systems brittle, so that they suffer from a poor resistance to crack initiation and propagation [1, 2]. It is well known that adding a block copolymer or rigid particles can improve the fracture toughness and crack growth initiation energy of epoxy systems [3–7]. Studying the cure kinetics of a given polymer system allows us to find semiempirical kinetic models that best describe the cure reaction and reveal variables that help establish the cure cycle. The popularity of the PPG-b-PEG-b-PPG triblock copolymer is due to its commercial availability, including different ratios of each block as well as the simplicity of the experimental procedure and the absence of any chemical synthesis or reaction with the epoxy system [4, 5, 8]. In our previous study [5] was observed the molar fraction of PEG in the copolymer struc
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