Preparation of pros-foam sheets and their epoxy foams using the solid-state carbamate-foaming technique

Lan, Du Ngoc Uy; Bethke, Christian; Altstaedt, Volker; Ruckdäschel, Holger

doi:10.1016/j.polymer.2022.125080

Cited by 2 publications

(3 citation statements)

References 23 publications

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“…In fact, these solid-state epoxies are carbamate-filled epoxy oligomers. They can be easily shaped into pellets or flat sheets [10]. These expandable epoxy preforms are suitable for designing epoxy foam products with various geometries.…”

Section: Gas Phase In Gel Stage  Foamablementioning

confidence: 99%

Novel Expandable Epoxy Beads and Epoxy Particle Foam

et al. 2022

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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.

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Section: Gas Phase In Gel Stage  Foamablementioning

confidence: 99%

Novel Expandable Epoxy Beads and Epoxy Particle Foam

et al. 2022

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“…[23][24][25] In the chemical foaming process, the bubble rate is difficult to control and results in the production of toxic gases. [26][27][28][29] Physical foaming, such as supercritical CO 2 foaming, is widely utilized but has a higher investment cost. 30,31 Acosta 32 created rigid epoxy foams using a photocurable approach in which the viscosity of the resin system had a substantial influence on the pore size of the foam, and the higher the viscosity, the larger the pore size.…”

Section: Introductionmentioning

confidence: 99%

“…Physical and chemical foaming are the most common epoxy foam molding techniques 23–25 . In the chemical foaming process, the bubble rate is difficult to control and results in the production of toxic gases 26–29 . Physical foaming, such as supercritical CO 2 foaming, is widely utilized but has a higher investment cost 30,31 .…”

Section: Introductionmentioning

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

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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.

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Preparation of pros-foam sheets and their epoxy foams using the solid-state carbamate-foaming technique

Cited by 2 publications

References 23 publications

Novel Expandable Epoxy Beads and Epoxy Particle Foam

Novel Expandable Epoxy Beads and Epoxy Particle Foam

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

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