Tailoring Epoxy Resin Foams by Pre-Curing with Neat Amine Hardeners and Its Derived Carbamates

Bethke, Christian; Goller, Sebastian Manfred; Ngoc, Uy Lan Du; Kaysser, Simon T.; Altstädt, Volker; Ruckdäschel, Holger

doi:10.3390/polym13081348

Cited by 7 publications

(5 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To decrease the particle size of the amino acid, the mixture of DGEBA and l -arginine is processed using a three-roll mill type EXAKT 120 EH-450 by EXAKT Advanced Technologies GmbH (Norderstedt, Germany). This method has already been applied for dispersing different fillers in epoxy resin [ 24 , 25 ] and proved to be advantageous compared to solvent-based methods [ 26 ]. The temperature of the rolls was set to 25 °C.…”

Section: Materials and Methodsmentioning

confidence: 99%

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

Rothenhäusler

Ruckdäschel

2022

Polymers

View full text Add to dashboard Cite

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.

show abstract

Section: Materials and Methodsmentioning

confidence: 99%

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

Rothenhäusler

Ruckdäschel

2022

Polymers

View full text Add to dashboard Cite

show abstract

“…The foam sandwich composite material was prepared by heating and locking the mold with a hot press. As illustrated in Figure 2, for the thermal expansion of resin and fiber prepreg curing mechanism, the foaming agent in the form of small microspheres present in the resin molecular chain produces a crosslinked network in the heating curing process to cover the expansion of the microspheres in the crosslinked network structure role of the stereotypes 43–45 . The expansion pressure generated by the expanding microspheres can cause the resin matrix and fiber prepregs to become intimately combined, thereby improving the mechanical characteristics of the skin and sandwich structure composites simultaneously.…”

Section: Methodsmentioning

confidence: 99%

Preparation of thermal expandable epoxy resin and properties of foam sandwich composites formed by thermal expansion molding process

Qin,

Mei,

Kang

et al. 2024

Polymer Composites

View full text Add to dashboard Cite

Thermal expansion molding process (TEMP) is a sophisticated molding technique for creating complex sandwich composites. The core key of TEMP is a high‐performance, thermally expandable resin film. In this study, the epoxy resin is used to create a specific crosslinking network that can provide the support force required for the stable molding of the vesicles during the expansion process of the foaming agent. The curing process of the resin was determined by analyzing the change in the exothermic amount of the epoxy resin during the curing process and the flow behavior of the resin. The pore size distribution of the epoxy foam was investigated, and the expansion force of the thermally expandable resin was tested. The TEMP molding process was compared with the vacuum bag press molding (VBPM) process. The TEMP molding technique increased tensile and compressive strength by about 25%, flexural strength by 34.5%, and shear strength by 54.5%. Finally, the section on microanalysis of the comparative materials and the short beam bending experiments of the sandwich structure provides a theoretical foundation for developing complicated sandwich structures.Highlights Preparation of thermally expandable epoxy prepregs with stabilized foaming by means of pre‐curing. The effects of curing temperature, foaming agent content and expansion multiplicity on the thermal expansion force of epoxy prepreg adhesives were investigated. Thermally expandable epoxy prepreg molding composites with different expansion multiplicities and analysis of the mechanical properties of the composites. Preparation of foam core sandwich composites by thermal expansion in‐mold monolithic molding process and their verification by bending experiments.

show abstract

“…The use of carbamate is beneficial for this solid-state method [7][8][9]. As a product of amine and carbon dioxide, carbamate decomposes at elevated temperatures to release CO 2 gas and recovered amine.…”

Section: Gas Phase In Gel Stage  Foamablementioning

confidence: 99%

Novel Expandable Epoxy Beads and Epoxy Particle Foam

et al. 2022

Self Cite

View full text Add to dashboard Cite

Expanded polymeric beads offer the advantage of being able to produce parts with complex geometries through a consolidation process. However, established polymeric beads are made of thermoplastics, deform and melt beyond their temperature services. In this manuscript, a new technique is proposed to fabricate expandable epoxy beads (EEBs), then expand and fuse them to produce epoxy particle foams (EPFs). This technique is called solid-state carbamate foaming technique. For production of EEBs, a mixture of epoxy, carbamate and hardener is prepared and poured into a 10 mL syringe. The mixture is manually extruded into 60 °C water to obtain a cylindric shape. The extrudate is then further cured to obtain an epoxy oligomer behaving rheological tan delta 3 and 2 at 60 °C. The extrudate is cut into pellets to obtain EEBs. The EEBs are then loaded into an aluminum mold and placed in an oven at 160 °C to expand, fuse to obtain EPFs of 212 kg/m3 and 258 kg/m3. The obtained EPFs provide a Tg of 150–154 °C. The fusion boundaries in EPFs are well formed. Thus, the produced EPFs exhibit a compressive modulus of 50–70 MPa, with a torsion storage modulus at 30 °C of 34–56 MPa.

show abstract

Tailoring Epoxy Resin Foams by Pre-Curing with Neat Amine Hardeners and Its Derived Carbamates

Cited by 7 publications

References 19 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

Preparation of thermal expandable epoxy resin and properties of foam sandwich composites formed by thermal expansion molding process

Novel Expandable Epoxy Beads and Epoxy Particle Foam

Contact Info

Product

Resources

About