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Effect of Resin and Blocked/Unblocked Hardener Mixture on the Production of Epoxy Foams with CO2 Blocked Hardener in Batch Foaming Process

1
Department of Polymer Engineering, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
2
School of Materials Engineering, University Malaysia Perlis, Kompleks Pusat Pengajian Jejawi II, Arau 02600, Perlis, Malaysia
3
Bavarian Polymer Institute and Bayreuth Institute of Macromolecular Research, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
*
Author to whom correspondence should be addressed.
Sharing first authorship.
Polymers 2019, 11(5), 793; https://doi.org/10.3390/polym11050793
Received: 9 April 2019 / Revised: 26 April 2019 / Accepted: 28 April 2019 / Published: 2 May 2019
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Abstract

The present study focuses on the processing and properties of epoxy foams by the use of CO2 blocked hardener N-aminoethylpiperazine (B-AEP) and different resins. Although some studies described the foaming with carbamates, little attention has been given to the interaction of resin properties (such as viscosity) on the foaming performance. Therefore, two resins, diglycidyl ether of bisphenol-A (DGEBA) and epoxy novolac (EN), as well as their 50:50 blend, were foamed with B-AEP and unblocked/blocked AEP hardener mixtures in a batch foaming process. Furthermore, the commercially available chemical blowing agent para-toluenesulfonyl hydrazide (TSH) was used as a benchmark for commonly used chemical blowing agents. The lowest density in this study was reached by the DGEBA+B-AEP system in the range of 215 kg/m3 with the drawback of an inhomogeneous cell structure and high cell size distribution. The best cell morphology and lowest cell size distribution was reached with the EN+15:85% unblocked:blocked hardener mixture, resulting in a density in the range of 394 kg/m3. A syntactic foam was achieved by a DGEBA+50:50% unblocked:blocked hardener mixture with a density of around 496 kg/m3. It was found that a higher viscosity of the resin lead to an increase in the density and a decrease in the cell size distribution range as a result of a closer expansion time window. View Full-Text
Keywords: epoxy foam; carbamate; CO2 foaming; epoxy resin; batch foaming; structural foam epoxy foam; carbamate; CO2 foaming; epoxy resin; batch foaming; structural foam
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Bethke, C.; Sanchez-Vazquez, S.A.; Raps, D.; Bakis, G.; Bard, S.; Du Ngoc, U.L.; Volker, A. Effect of Resin and Blocked/Unblocked Hardener Mixture on the Production of Epoxy Foams with CO2 Blocked Hardener in Batch Foaming Process. Polymers 2019, 11, 793.

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