Rheokinetic and Dynamic Mechanical Analysis of Tetrafunctional                 Epoxy/anhydride Mixtures. Influence of Stoichiometry and Cure Conditions

Corcuera, María Ángeles; Caba, Koro de la; Gabilondo, Nagore; Marieta, Cristina; Kortaberría, Galder; Eceiza, Arantxa

doi:10.1177/0954008306050009

Cited by 3 publications

(3 citation statements)

References 33 publications

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“…So far, the highest stiffnesses and strengths are achieved by using anhydride hardeners, which exhibit a rigid ring structure . Full conversions of epoxy and anhydride groups are obtained for stoichiometric ratios R ( = anhydride/epoxy) from R = 0.7–0.9, depending on the applied anhydride type …”

Section: Introduction and Scopementioning

confidence: 99%

Anhydride Cured Bio‐Based Epoxy Resin: Effect of Moisture on Thermal and Mechanical Properties

Anusic

Resch‐Fauster

Mahendran

et al. 2019

Macro Materials & Eng

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This paper describes the development of a novel thermoset based on epoxidized hemp seed oil. The optimization of the hardener (anhydride) and crosslinking accelerator (2‐ethylimidazol) concentration as well as the curing parameters are discussed in detail. The optimized material exhibits a bio‐based carbon portion of 57.5 wt% and represents an innovative and sustainable substitute for fully petrochemical‐based resins in terms of thermal and mechanical performance characteristics. However, also a major challenge with regard to practical applications of (bio‐based) thermosets with anhydride curing agent thermosets is identified and addressed: the sensitivity to moisture absorption both during curing and in the fully cured state.

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Section: Introduction and Scopementioning

confidence: 99%

Anhydride Cured Bio‐Based Epoxy Resin: Effect of Moisture on Thermal and Mechanical Properties

Anusic

Resch‐Fauster

Mahendran

et al. 2019

Macro Materials & Eng

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“…As already mentioned in Section 2.3, the optimal R for epoxy resins cured with conventional anhydrides is about 0.8. [ 43,44 ] In conclusion, the carboxyl group of the resin acids has a significant influence on the curing kinetics and the resulting network structure. Interestingly, T g plateaus despite the constant change in ν C , which indicates that the glass transition temperature is not only influenced by ν C but also by the types of chemical bonds that form and the ratio between the aromatic epoxy resin and the cyclic curing agent.…”

Section: Resultsmentioning

confidence: 99%

Influence of the Stoichiometric Ratio on the Curing Kinetics and Mechanical Properties of Epoxy Resin Cured with a Rosin‐Based Anhydride

Rothenhäusler,

Kettenbach,

Ruckdaeschel

2023

Macro Materials & Eng

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Bio‐based alternatives for petroleum‐based epoxy resin curing agents, such as maleopimaric acid (MPA), are indispensable for sustainable fiber reinforced polymer composites with thermosetting matrices. However, previous investigations disregarded the importance of choosing the right stoichiometric ratio R between the anhydride groups in the rosin‐based curing agent and the epoxy groups in the resin. Therefore, the influence of R on the curing kinetics and mechanical properties of an epoxy resin cured with a rosin‐based anhydride is studied. Here, Fourier‐transform infrared spectroscopy (FT–IR) indicates that for R ⩾ 0.9 unreacted anhydride groups are present in the thermoset. Consequently, the network density decreases and the glass transition temperature Tg drops by about 40 °C. On the other hand, the steric hindrance of unreacted functional groups for R ⩾ 0.9, increases the flexural modulus and the reduced network density improves fracture toughness. The results indicate that the best R for overall high mechanical performance and good processability is preferably low (R ⩽ 0.7). Here, a low R results in a high Tg and good processability due to a low viscosity. However, the latency of the mixtures is low and therefore, the mixtures are not fit for processing via prepreg technology.

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“…On the other hand, to convert epoxidized vegetable oil into a crosslinked thermoset material, hardeners such as anhydrides or amines are used [ 10 , 17 ]. Anhydrides are the most employed curing agents, but they can present problems due to a susceptibility to hydrolytic degradation [ 31 ]. This aspect can be directly related to the moisture sensitivity of the epoxy resin and, furthermore, it can be increased if the epoxy resin is used to develop composites with natural fibers, which can contain moisture contents between 3 and 13% [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Epoxidized and Maleinized Hemp Oil to Develop Fully Bio-Based Epoxy Resin Based on Anhydride Hardeners

et al. 2023

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The present work aims to develop thermosetting resins using epoxidized hemp oil (EHO) as a bio-based epoxy matrix and a mixture of methyl nadic anhydride (MNA) and maleinized hemp oil (MHO) in different ratios as hardeners. The results show that the mixture with only MNA as a hardener is characterized by high stiffness and brittleness. In addition, this material is characterized by a high curing time of around 170 min. On the other hand, as the MHO content in the resin increases, the mechanical strength properties decrease and the ductile properties increase. Therefore, it can be stated that the presence of MHO confers flexible properties to the mixtures. In this case, it was determined that the thermosetting resin with balanced properties and high bio-based content contains 25% MHO and 75% MNA. Specifically, this mixture obtained a 180% higher impact energy absorption and a 195% lower Young’s modulus than the sample with 100% MNA. Also, it has been observed that this mixture has significantly shorter times than the mixture containing 100% MNA (around 78 min), which is of great concern at an industrial level. Therefore, thermosetting resins with different mechanical and thermal properties can be obtained by varying the MHO and MNA content.

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Rheokinetic and Dynamic Mechanical Analysis of Tetrafunctional Epoxy/anhydride Mixtures. Influence of Stoichiometry and Cure Conditions

Cited by 3 publications

References 33 publications

Anhydride Cured Bio‐Based Epoxy Resin: Effect of Moisture on Thermal and Mechanical Properties

Anhydride Cured Bio‐Based Epoxy Resin: Effect of Moisture on Thermal and Mechanical Properties

Influence of the Stoichiometric Ratio on the Curing Kinetics and Mechanical Properties of Epoxy Resin Cured with a Rosin‐Based Anhydride

Epoxidized and Maleinized Hemp Oil to Develop Fully Bio-Based Epoxy Resin Based on Anhydride Hardeners

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