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. 2021 Nov 11;13(22):3893.
doi: 10.3390/polym13223893.

Investigations on Epoxy-Carbamate Foams Modified with Different Flame Retardants for High-Performance Applications

Simon T Kaysser  1   2 , Christian Bethke  1 , Isabel Fernandez Romero  2 , Angeline Wo Weng Wei  2 , Christian A Keun  2 , Holger Ruckdäschel  1   3   4 , Volker Altstädt  1   3   4
Affiliations

Investigations on Epoxy-Carbamate Foams Modified with Different Flame Retardants for High-Performance Applications

Simon T Kaysser et al. Polymers (Basel). .

Abstract

In transport sectors such as aviation, automotive and railway, materials combining a high lightweight potential with high flame retardant properties are in demand. Polymeric foams are suitable materials as they are lightweight, but often have high flammability. This study focuses on the influence of different flame retardants on the burning behavior of Novolac based epoxy foams using Isophorone Diamine carbamate (B-IPDA) as dual functional curing and blowing agent. The flame retardant properties and possible modifications of these foams are systematically investigated. Multiple flame retardants, representing different flame retardant mechanisms, are used and the effects on the burning behavior as well as mechanical and thermal properties are evaluated. Ammonium polyphosphate (APP), used with a filler degree of 20 wt.% or higher, functions as the best performing flame retardant in this study.

Keywords: blowing agent; carbamate; epoxy foam; flame retardance; latent curing agent.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Left: small aluminum molds with a cavity of 30 × 30 × 10 mm3, Middle: mold filled with foam formulation, Right: halved foam specimen.
Figure 2
Figure 2
SEM images taken from EN/B-IPDA foams without particle modification, Neat (a), with 30 wt.% ATH (b,c) and 40 wt.% ATH of different particle size A20 (d) and A2 (e).
Figure 3
Figure 3
Compression curves of EP foams modified with ATH (a), APP (b), DOPO (c) and MP (d).
Figure 4
Figure 4
Average flame-off time of flame retardant modified EN/B-IPDA foam specimens ref. to UL94 Horizontal Burn (from left to right: neat, ATH, APP, DOPO, MP); specimens marked with (F) failed the UL94 HB criteria.
Figure 5
Figure 5
SEM images taken von EN/B-IPDA foams without particle modification, Neat (a), with APP 15 wt.% (b), 20 wt.% (c), 30 wt.% (d).
Figure 6
Figure 6
SEM images taken von EN/B-IPDA foams without particle modification, Neat (a), with DOPO 10 wt.% (b), 20 wt.% (c), 30 wt.% (d).
Figure 7
Figure 7
SEM images taken von EN/B-IPDA foams without particle modification, Neat (a), with MP 10 wt.% (b), 15 wt.% (c), 20 wt.% (d).
Figure 8
Figure 8
Average specific compressive strength (compressive strength normalized by the foam density), compression tests ref. to DIN EN ISO 844:2014-11, preload 1 N, test speed 1 mm/min, max. deformation 70% (dark grey) and average flame-off time in horizontal burn tests ref. to UL94 with reduced specimen size (light grey).
See this image and copyright information in PMC

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