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

DOI zum Zitieren der Version auf EPub Bayreuth: https://doi.org/10.15495/EPub_UBT_00006527
URN to cite this document: urn:nbn:de:bvb:703-epub-6527-9

Title data

Du Ngoc, Uy Lan ; 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 der Verlagsversion: https://doi.org/10.3390/polym13152441

	Format: PDF Name: polymers-13-02441-v2.pdf Version: Published Version Available under License Creative Commons BY 4.0: Attribution
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Project information

Project title:	Project's official title Project's id No information AL 474/49-1 Open Access Publizieren No information
Project financing:	Deutsche Forschungsgemeinschaft

Abstract

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
Keywords:	solid-state foaming; epoxy foam; CO₂ batch foaming; storage modulus
DDC Subjects:	600 Technology, medicine, applied sciences > 620 Engineering
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 > Central research institutes > Bayreuth Institute of Macromolecular Research - BIMF Research Institutions > Affiliated Institutes > Bavarian Polymer Institute (BPI) Faculties Faculties > Faculty of Engineering Science Faculties > Faculty of Engineering Science > Former Professors Faculties > Faculty of Engineering Science > Chair Polymer Materials Research Institutions Research Institutions > Central research institutes Research Institutions > Affiliated Institutes
Language:	English
Originates at UBT:	Yes
URN:	urn:nbn:de:bvb:703-epub-6527-9
Date Deposited:	21 Jul 2022 06:51
Last Modified:	21 Jul 2022 06:51
URI:	https://epub.uni-bayreuth.de/id/eprint/6527

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