Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates

Duemichen, Erik; Javdanitehran, Mehdi; Erdmann, Maren; Trappe, Volker; Sturm, Heinz; Braun, Ulrike; Ziegmann, Gerhard

doi:10.1016/j.tca.2015.08.008

Cited by 45 publications

(27 citation statements)

References 50 publications

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“…The values of the two activation energies E 1 and E 2 are, respectively, 61.96 and 43.21 kJ/mol. The value of the activation energy E 1 matches the value of a similar epoxy system, 42 showing credibility of the chosen reaction model. The values of the two pre‐exponential factors were respectively 1.23 × 10 6 s −1 and 2.66 × 10 3 s −1 .…”

Section: Resultssupporting

confidence: 63%

Cure simulations of thick adhesive bondlines for wind energy applications

Cassano

Dev

Maiarù

et al. 2020

J of Applied Polymer Sci

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Curing of adhesive bondlines is a critical and time-consuming operation in wind turbine blade manufacturing. Significant variation in adhesive thickness can lead to important differences in thermal histories trough the adhesive bonds due to the exothermic nature of the cure process. Reducing bondline cure cycle time and avoiding adhesive overheating are two competing factors in the design of cure temperature cycles. Predictive models on the impact of adhesive thickness variability in bondline cure temperature cycle is currently limited. Adhesive curing and temperature evolution can be simulated by finite element (FE) models coupling the heat transfer problem with the cure kinetics of the adhesive. The cure kinetics of the adhesive system was characterized by isothermal differential scanning calorimetry experiments and implemented in the FE software Abaqus/CAE by user subroutines. Predictions from the FE model were validated experimentally against temperature readings from the curing of 10, 20, and 30 mm thick adhesive bondlines. To highlight the role that predictive models potentially have in the optimization of bondline cure cycles a 2D cross section model representing the trailing edge of a wind turbine blade was used as case study. It was demonstrated that computational models enable customizing cure profiles for nonuniform adhesive thicknesses, ensuring fully cured bondlines with acceptable mechanical properties.

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Section: Resultssupporting

confidence: 63%

Cure simulations of thick adhesive bondlines for wind energy applications

Cassano

Dev

Maiarù

et al. 2020

J of Applied Polymer Sci

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show abstract

“…Moreover, Kissinger method simplifies the activation energy and pre‐exponential factor as being a constant value during the whole reaction, which possible could be an over‐simplification for complex reactions. However, this method is applied in many studies for kinetic analysis of epoxy systems and reported to be a feasible estimation of the model starting parameter …”

Section: Theoriotical Backgroundmentioning

confidence: 99%

Influence of model parameter estimation methods and regression algorithms on curing kinetics and rheological modelling

Abliz

Artys

Ziegmann

2017

J of Applied Polymer Sci

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The accuracy of the phenomenological curing and rheological models are strongly related to the estimated start parameters and selected regression algorithms. Considering the versatile methods for model start parameter estimation (model‐free vs. model‐fitting, dynamic vs. isothermal) and regression analysis algorithm (linear vs. nonlinear, single‐target vs. multi‐target), this paper investigates the theoretical basis and influence of these aspects on the model development process and model quality. The curing kinetics is modelled by model‐free and model‐fitting start parameters and different regression algorithms, followed by cross model validation at the final. The results showed that the different parameter estimation methods and evaluation algorithms have a remarkable influence on the final model parameters and its quality. The study shows the correlation between the different aspects and provides a basis for better selection of model parameter evaluation methods and regression algorithms for model development with improved quality and accuracy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45137.

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“…Epoxy resins are a class of materials of great significance since they can be used stand-alone for the manufacturing of versatile products, but most importantly they serve as matrix in fiber-reinforced polymer composites that find application in various sectors, such as aerospace, wind energy, marine industry, etc [1]. One of the key parameters to obtain highperformance epoxy systems/composites is related to the curing process during which the liquid components of the resin system are converted into a rigid polymer network with increased stiffness, strength, and temperature/dimensional stability [1,2]. Typically in a two-component system, this occurs by allowing the resin to react with the hardener for several hours depending on the chemistry of the system and the applied temperature.…”

Section: Introductionmentioning

confidence: 99%

Fast curing versus conventional resins – degradation due to hygrothermal and UV exposure

Barkoula¹,

Karabela²,

Zafeiropoulos³

et al. 2020

Express Polym. Lett.

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In the current paper, three resin systems are investigated, the first is a high temperature fast curing system, the second is a high-temperature system that requires several hours to cure and the third is a slow room temperature curing system. All systems are exposed to hygrothermal and combined moisture/temperature/UV protocols, and their durability is assessed using Fourier transform infrared (FTIR) spectroscopy, mechanical and thermomechanical characterization. The conventional slow curing system presents a wide distribution of polymer chains that leads in excess free volume/increased susceptibility to water. The medium curing system is more homogenous and shows lower absorption profiles. The fast curing system shows two network domains, one that is more crosslinked and contributes towards higher free volume/water absorption and the other that is partially cured and supports chain scission/leaching processes during exposure. Continuation of crosslinking prevails in conventional resins upon hygrothermal and combined UV exposure. At the same time antagonistic effects (i.e. continuation of the crosslinking process versus plasticization, chain scission, and leaching) are observed in medium curing and fast curing systems upon exposure.

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Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates

Cited by 45 publications

References 50 publications

Cure simulations of thick adhesive bondlines for wind energy applications

Cure simulations of thick adhesive bondlines for wind energy applications

Influence of model parameter estimation methods and regression algorithms on curing kinetics and rheological modelling

Fast curing versus conventional resins – degradation due to hygrothermal and UV exposure

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