Physical aging and toughness degradation in core–shell rubber modified epoxy polymers
Abstract
Understanding how physical aging influences fracture resistance is essential for the reliable use of rubber-toughened epoxy polymers in structural applications. However, the influence of physical aging on their fracture behaviour remains poorly quantified. In this study, an amine–cured, DGEBA epoxy polymer containing 3, 6 and 9 wt% core–shell rubber (CSR) nanoparticles was aged isothermally at 80 °C for up to one year. The evolution of fracture energy was characterised using single-edge notched bending (SENB) alongside measurements of enthalpy recovery and multiaxial yield behaviour to establish the underlying changes in matrix response. Physical aging produced measurable increases in compressive yield stresses, indicating heightened pressure sensitivity of the matrix. These changes were associated with significant reductions in fracture energy, the severity of which depended strongly on CSR content. The results are consistent with aging-induced reduction in the effectiveness of the plastic deformation processes responsible for enhanced fracture performance at the crack tip. Comparison with the Huang-Kinloch model shows good agreement for some compositions and aging states, but reveals a shifting interplay between matrix properties, interphase structure and particle spacing as aging progresses. Thermal rejuvenation above the glass transition temperature restored a large fraction of the fracture energy lost during aging, indicating that the degradation is largely reversible. The results provide a quantitative link between physical aging, yield behaviour and fracture energy in rubber-modified epoxy polymers and highlight the need to account for aging induced changes in fracture resistance when assessing the long-term reliability of structural polymer systems.
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BibTeX
@article{incerti2026physical,
title = {{Physical aging and toughness degradation in core–shell rubber modified epoxy polymers}},
author = {Daniele Incerti and Clemence Rouge and Alexander Fergusson and Declan Carolan},
journal = {Engineering Fracture Mechanics},
year = {2026},
month = oct,
doi = {10.1016/j.engfracmech.2026.112714},
url = {https://hal.science/hal-05791287v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Physical aging and toughness degradation in core–shell rubber modified epoxy polymers
AU - Daniele Incerti
AU - Clemence Rouge
AU - Alexander Fergusson
AU - Declan Carolan
PY - 2026
DA - 2026/10/10
JO - Engineering Fracture Mechanics
DO - 10.1016/j.engfracmech.2026.112714
UR - https://hal.science/hal-05791287v1
AB - Understanding how physical aging influences fracture resistance is essential for the reliable use of rubber-toughened epoxy polymers in structural applications. However, the influence of physical aging on their fracture behaviour remains poorly quantified. In this study, an amine–cured, DGEBA epoxy polymer containing 3, 6 and 9 wt% core–shell rubber (CSR) nanoparticles was aged isothermally at 80 °C for up to one year. The evolution of fracture energy was characterised using single-edge notched bending (SENB) alongside measurements of enthalpy recovery and multiaxial yield behaviour to establish the underlying changes in matrix response. Physical aging produced measurable increases in compressive yield stresses, indicating heightened pressure sensitivity of the matrix. These changes were associated with significant reductions in fracture energy, the severity of which depended strongly on CSR content. The results are consistent with aging-induced reduction in the effectiveness of the plastic deformation processes responsible for enhanced fracture performance at the crack tip. Comparison with the Huang-Kinloch model shows good agreement for some compositions and aging states, but reveals a shifting interplay between matrix properties, interphase structure and particle spacing as aging progresses. Thermal rejuvenation above the glass transition temperature restored a large fraction of the fracture energy lost during aging, indicating that the degradation is largely reversible. The results provide a quantitative link between physical aging, yield behaviour and fracture energy in rubber-modified epoxy polymers and highlight the need to account for aging induced changes in fracture resistance when assessing the long-term reliability of structural polymer systems.
SN - 0013-7944
ER -