TY - JOUR
T1 - Redox cationic frontal polymerization
T2 - a rapid curing approach for carbon fiber-reinforced composites with high fiber content
AU - Malik, Muhammad Salman
AU - Wolfahrt, Markus
AU - Pinter, Gerald
AU - Schlögl, Sandra
N1 - Publisher Copyright: © The Author(s) 2024.
PY - 2024/2/22
Y1 - 2024/2/22
N2 - Conventional frontal polymerization processes for epoxy-based composites rely on cations and radicals generated by a short (and local) light or heat stimulus in the presence of an iodonium salt and a radical thermal initiator. However, due to heat losses, the propagation of the exothermic curing front is often limited by sample geometry and filler concentration. Redox cationic frontal polymerization (RCFP) is a promising approach to radically expand the composition and design options of frontally cured epoxy-based composites. By adding stannous octoate as reducing agent, a higher number of radicals and cations are generated at lower temperature, which yields highly cured composite even at elevated filler content. In the current study, RCFP was used to cure standard unidirectional carbon fiber-reinforced composites based on a commercially available epoxy resin and the properties were compared with its anhydride hardener-cured counterpart. Cure degree and thermal properties of the resins were determined by ATR FT-IR spectroscopy and DMA analysis. Subsequently, unidirectional composites with a fiber volume content of ~ 60% were produced via vacuum infusion and subjected to DMA, tensile, compression, and inter-laminar shear tests. The results showed a remarkable similarity between mechanical properties of RCFP and anhydride hardener-cured composites. The RCFP-cured composites exhibited even a higher damping resistance and compression strength than anhydride hardener-cured composites. The results show that RCFP allows for a significant reduction in the curing time (from several hours to 60 min), while it yields composites with properties comparable to classic anhydride-cured systems. Graphical abstract: (Figure presented.).
AB - Conventional frontal polymerization processes for epoxy-based composites rely on cations and radicals generated by a short (and local) light or heat stimulus in the presence of an iodonium salt and a radical thermal initiator. However, due to heat losses, the propagation of the exothermic curing front is often limited by sample geometry and filler concentration. Redox cationic frontal polymerization (RCFP) is a promising approach to radically expand the composition and design options of frontally cured epoxy-based composites. By adding stannous octoate as reducing agent, a higher number of radicals and cations are generated at lower temperature, which yields highly cured composite even at elevated filler content. In the current study, RCFP was used to cure standard unidirectional carbon fiber-reinforced composites based on a commercially available epoxy resin and the properties were compared with its anhydride hardener-cured counterpart. Cure degree and thermal properties of the resins were determined by ATR FT-IR spectroscopy and DMA analysis. Subsequently, unidirectional composites with a fiber volume content of ~ 60% were produced via vacuum infusion and subjected to DMA, tensile, compression, and inter-laminar shear tests. The results showed a remarkable similarity between mechanical properties of RCFP and anhydride hardener-cured composites. The RCFP-cured composites exhibited even a higher damping resistance and compression strength than anhydride hardener-cured composites. The results show that RCFP allows for a significant reduction in the curing time (from several hours to 60 min), while it yields composites with properties comparable to classic anhydride-cured systems. Graphical abstract: (Figure presented.).
KW - Cations
KW - Composites
KW - Epoxy
KW - Frontal polymerization
KW - Radicals
KW - Redox reactions
UR - http://www.scopus.com/inward/record.url?scp=85185691009&partnerID=8YFLogxK
U2 - 10.1007/s00706-023-03168-y
DO - 10.1007/s00706-023-03168-y
M3 - Article
AN - SCOPUS:85185691009
SN - 0026-9247
VL - 155.2024
SP - 205
EP - 217
JO - Monatshefte fur Chemie
JF - Monatshefte fur Chemie
IS - 2
ER -