Fast curing unidirectional carbon epoxy prepregs based on a semi-latent hardener: The influence of ambient aging on the prepregs Tg0, processing behavior and thus derived interlaminar performance of the composite

Hübner, Fabian; Meuchelböck, Johannes; Wolff‐Fabris, Felipe; Mühlbach, Martin; Altstädt, Volker; Ruckdäschel, Holger

doi:10.1016/j.compscitech.2021.109047

Cited by 18 publications

(12 citation statements)

References 31 publications

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“…The

of Argopox-1 and Argopox-2.5 are comparable to the glass transition temperatures of DGEBA cured with l -tryptophan [ 11 , 13 , 14 , 15 ]. Still, the

of DGEBA cured with dicyandiamide is considerably higher at around 140 °C [ 22 , 28 ]. The difference in

most likely stems from the aliphatic side chain of l -arginine which contains three carbon atoms between its

-amine group and the next functional group.…”

Section: Resultsmentioning

confidence: 99%

“…The

of Argopox-1 shifts from −19.3 °C to −14 °C after 60 d while the same shift in

of Argopox-2.5 is reached after a little more than a month. Hübner et al found a shift of about 5 °C in

in an epoxy resin cured with dicyandiamide and accelerated with DYHARD ® UR500 as result of aging at room temperature after 91 d [ 22 ]. This shows that the l -arginine-cured epoxy resin is less latent, meaning more reactive, than the petroleum-based material system.…”

Section: Resultsmentioning

confidence: 99%

“…For thermosetting resins, the storage period at room temperature in which the compound’s viscosity doubles due to pre-conversion is called the pot-life of the material system [ 21 ]. However, aging does not only affect the viscosity of the uncured resin system but also alters the processing properties of the prepreg, such as tack, and the matrix-driven mechanical properties of the cured laminate, such as tensile strength perpendicular to fiber direction and interlaminar shear strength [ 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

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l-Arginine as a Bio-Based Curing Agent for Epoxy Resins: Glass Transition Temperature, Rheology and Latency

Rothenhäusler

Ruckdäschel

2022

Polymers

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The need for sustainable practices in the processing chain of fiber-reinforced thermosets has led to the development of bio-based epoxy resins and curing agents. As a contribution to sustainable composites, this study focuses on the glass transition temperature (Tg), viscosity and latency of diglycidyl ether of bisphenol a (DGEBA) cured with l-arginine in the presence of a urea-based accelerator. These characteristics are decisive features for application as a matrix in fiber-reinforced polymer composites produced via prepreg technology in which low viscosity and sufficient latency, meaning low reactivity of the one-component system, are necessary. The homogeneous mixture of amino acid and epoxy resin was prepared via three-roll milling. Two formulations, Argopox-1 with 1wt.% accelerator and Argopox-2.5 with 2.5wt.% accelerator, were prepared and parts of each formulation were stored at 22∘C and −18∘C, respectively. Both formulations were tested via differential scanning calorimetry (DSC) and small amplitude oscillatory shear rheology (SAOS) after 0 day, 30 day, 60 day, 90 day and 180 day of storage to determine the influence of accelerator weight fraction, storage temperature and storage period on the glass transition temperature of the uncured resin system Tg0, and their viscosity. The Tg of the thermosets is about 100∘C. The DSC and SAOS measurements show that the Tg0 of Argopox-1 shifts about 5∘C in 60 day, while its viscosity is still low enough to be processed in a prepreg production line. Furthermore, Argopox-1 is storable for at least 180 day at −18∘C without significant changes in its Tg0 and viscosity. Consequently, Argopox-1 possesses a sufficiently high Tg and adequate latency, as well as a low viscosity for application as prepreg matrix material.

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“…The

of Argopox-1 and Argopox-2.5 are comparable to the glass transition temperatures of DGEBA cured with l -tryptophan [ 11 , 13 , 14 , 15 ]. Still, the

of DGEBA cured with dicyandiamide is considerably higher at around 140 °C [ 22 , 28 ]. The difference in

most likely stems from the aliphatic side chain of l -arginine which contains three carbon atoms between its

-amine group and the next functional group.…”

Section: Resultsmentioning

confidence: 99%

“…The

of Argopox-1 shifts from −19.3 °C to −14 °C after 60 d while the same shift in

of Argopox-2.5 is reached after a little more than a month. Hübner et al found a shift of about 5 °C in

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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l-Arginine as a Bio-Based Curing Agent for Epoxy Resins: Glass Transition Temperature, Rheology and Latency

Rothenhäusler

Ruckdäschel

2022

Polymers

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“…cure times of less than 20 min have been used for rapid production of thermosetting polymer composites. 8 However, such resin systems have a limited pot life and produce a high amount of exothermic heat from bulk polymerization, resulting in material degradation, buildup of residual stresses, and poor dimensional stability of produced composite parts. 9,10 Radiation curing is an alternative approach for manufacturing thermoset polymer composites, where various electromagnetic waves within the electromagnetic spectrum (e.g., ultraviolet, gamma, radio frequency, infrared, and microwave) are used to provide energy for curing of composites.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The growing demand for FRPCs in various fields has motivated the development of new composite materials and manufacturing techniques that enable low cost, rapid, and energy-efficient manufacture of composite materials with improved performance. Fast curing resin formulations with cure times of less than 20 min have been used for rapid production of thermosetting polymer composites . However, such resin systems have a limited pot life and produce a high amount of exothermic heat from bulk polymerization, resulting in material degradation, buildup of residual stresses, and poor dimensional stability of produced composite parts. , Radiation curing is an alternative approach for manufacturing thermoset polymer composites, where various electromagnetic waves within the electromagnetic spectrum (e.g., ultraviolet, gamma, radio frequency, infrared, and microwave) are used to provide energy for curing of composites. − Although each of these curing methods have their own distinct advantages, none of them have gained widespread acceptance in the industry due to their specific limitations.…”

Section: Introductionmentioning

confidence: 99%

Rapid and Energy-Efficient Frontal Curing of Multifunctional Composites Using Integrated Nanostructured Heaters

Naseri

Yourdkhani

2022

ACS Appl. Mater. Interfaces

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Current technologies for the manufacture of fiberreinforced polymer composites are energy-intensive, environmentally unfriendly, and time-consuming and require expensive equipment and resources. In addition, composites typically lack key nonstructural functionalities (e.g., electrical conductivity for deicing, lightning strike protection, and structural health monitoring), which are crucial to many applications such as aerospace and wind energy. Here, we present a new approach for rapid and energy-efficient manufacturing of multifunctional composites without using traditional expensive autoclaves, ovens, or heated molds used for curing of composites. Our approach is predicated on embedding a thin conductive nanostructured paper in the composite layup to act as a resistive heater for triggering frontal polymerization of the matrix thermosetting resin of the composite laminate. Upon passing electric current, the nanostructured paper quickly heats up and initiates frontal polymerization, which then rapidly propagates through the thickness of the laminate, resulting in rapid curing of composites (within seconds to few minutes) irrespective of the size of the composite laminate. The integrated nanostructured paper remains advantageous during the service of the composite part by imparting new functionalities (e.g., deicing) to the cured composite, owing to its excellent electrical conductivity and electrothermal properties. In this work, we first study the influence of several composite processing parameters on the electrothermal properties of the nanostructured paper and determine the power required for rapid initiation of frontal polymerization. We then successfully fabricate a 10 cm × 10 cm composite panel within 1 min using only 4.49 kJ of energy, which is 4 orders of magnitude less than the energy consumed by the traditional bulk, oven-curing technique. Detailed experiments are conducted to provide an in-depth understanding of the effect of heater position, tooling material, and input power on frontal curing of composite laminates. The multifunctional response of produced composites is demonstrated by performing a deicing experiment, where a 50 × 50 × 3 mm 3 cube of ice is completely melted within 3 min using an input power of 77 W.

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Supported Ionic Liquid‐Phase Materials (SILP) as a Multifunctional Group of Highly Stable Modifiers and Hardeners for Carbon and Flax Epoxy Composites

Zielinski,

Szpecht,

Kukawka

et al. 2024

ChemPlusChem

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This paper introduces a novel approach to enhance epoxy resin formulations by using SILP materials as multifunctional hardeners and fillers in composite structures reinforced with carbon and flax fibers. This study explores the integration of ionic liquids (ILs) onto a silica support structure, presenting various permutations involving silica selection, ionic liquid choice, and concentration. The focus of this study was to elucidate the influence of SILP on resin curing ability and the mechanical properties of the resulting composites. Detailed research was conducted, including Brunauer‐Emmett‐Teller analysis (BET) for SILP materials and curing characterization for epoxy resin formulations with different SILP materials. Furthermore, the mechanical properties of the obtained composites were determined by Scanning Electron Microscopy analysis (SEM) (the force at break, the maximum elongation at break, tensile strength, and modulus of elasticity). Through SILP incorporation, the mechanical properties of composites, including the modulus of elasticity and tensile strength, are substantially improved, a phenomenon akin to traditional filler effects. The findings highlight SILP materials as prospective candidates for concurrent hardening and filling roles within composites (through a single‐step procedure, with prolonged storage stability and controlled processing conditions), particularly pertinent as the composite industry veers toward epoxy bioresins necessitating liquefaction via temperature application.

show abstract

Fast curing unidirectional carbon epoxy prepregs based on a semi-latent hardener: The influence of ambient aging on the prepregs Tg0, processing behavior and thus derived interlaminar performance of the composite

Cited by 18 publications

References 31 publications

l-Arginine as a Bio-Based Curing Agent for Epoxy Resins: Glass Transition Temperature, Rheology and Latency

l-Arginine as a Bio-Based Curing Agent for Epoxy Resins: Glass Transition Temperature, Rheology and Latency

Rapid and Energy-Efficient Frontal Curing of Multifunctional Composites Using Integrated Nanostructured Heaters

Supported Ionic Liquid‐Phase Materials (SILP) as a Multifunctional Group of Highly Stable Modifiers and Hardeners for Carbon and Flax Epoxy Composites

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