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New Insights on Expandability of Pre-Cured Epoxy Using a Solid-State CO₂-Foaming Technique

Title data

Du, Uy Lan Ngoc ; Bethke, Christian ; Altstädt, Volker ; Ruckdäschel, Holger:
New Insights on Expandability of Pre-Cured Epoxy Using a Solid-State CO₂-Foaming Technique.
In: Polymers. Vol. 13 (2021) Issue 15 . - No. 2441.
ISSN 2073-4360
DOI: https://doi.org/10.3390/polym13152441

Project information

Project title:
Project's official titleProject's id
No informationAL 474/49-1
Open Access PublizierenNo information

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

Foaming an epoxy is challenging because the process involves the curing reaction of epoxy and hardener (from monomer to oligomer, to a gel and a final three-dimensional crosslinked network) and the loading of gas phase into the epoxy phase to develop the cellular structure. The latter process needs to be carried out at the optimum curing stage of epoxy to avoid cell coalescence and to allow expansion. The environmental concern regarding the usage of chemical blowing agent also limits the development of epoxy foams. To surmount these challenges, this study proposes a solid-state CO2 foaming of epoxy. Firstly, the resin mixture of diglycidylether of bisphenol-A (DGEBA) epoxy and polyamide hardener is pre-cured to achieve various solid-state sheets (preEs) of specific storage moduli. Secondly, these preEs undergo CO₂ absorption using an autoclave. Thirdly, CO₂ absorbed preEs are allowed to free-foam/expand in a conventional oven at various temperatures; lastly, the epoxy foams are post-cured. PreE has a distinctive behavior once being heated; the storage modulus is reduced and then increases due to further curing. Epoxy foams in a broad range of densities could be fabricated. PreE with a storage modulus of 4 × 10⁴–1.5 × 10⁵ Pa at 30 °C could be foamed to densities of 0.32–0.45 g/cm³. The cell morphologies were revealed to be star polygon shaped, spherical and irregularly shaped. The research proved that the solid-state CO₂-foaming technique can be used to fabricate epoxy foams with controlled density.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: solid-state foaming; epoxy foam; CO₂ batch foaming; storage modulus
Institutions of the University: Faculties > Faculty of Engineering Science > Former Professors > Chair Polymer Materials - Univ.-Prof. Dr.-Ing. Volker Altstädt
Faculties > Faculty of Engineering Science > Chair Polymer Materials > Chair Polymer Materials - Univ.-Prof. Dr.-Ing. Holger Ruckdäschel
Research Institutions > Research Centres > Bayreuth Institute of Macromolecular Research - BIMF
Research Institutions > Affiliated Institutes > Bavarian Polymer Institute (BPI)
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 09 Nov 2021 10:38
Last Modified: 09 Nov 2021 10:38
URI: https://eref.uni-bayreuth.de/id/eprint/67716