Abstract
A remarkable synergistic increase in fracture toughness by 130% is demonstrated for a CFRP high performance epoxy composite when adding an equal weight combination of phenoxy thermoplastic and core-shell rubber (CSR) toughening agents, as compared to a single toughener at a comparable total concentration of around 10 wt%. The dual-toughened matrix exhibits an unusual morphological arrangement of the two toughener agents. The interlaminar shear strength of the composites is also synergistically improved by about 75% as compared to the reference while the compression modulus reduction and viscosity increase are significantly smaller than for the single phenoxy toughened system. A partial filtering of the CSR particles by the dense CF fabric during pre-pregging leads to a less than optimum CSR dispersion in the composites, showing that the synergy can be further optimized, possibly to the same level as the unreinforced systems.
Highlights
We study the effect of the synergistic combination of two different kinds of toughening agents on the performance of a highly cross-linked epoxy resin and the corresponding structural composites
KaneAce MX-416 provided by Kaneka (Tokyo, Japan) was a masterbatch comprised of 25% core-shell rubber with polybutadiene core and PMMA shell pre-dispersed in TGDDM
Dynamical Mechanical Thermal Analysis (DMTA) measurements were performed on cured neat epoxy (EP) as well as on blends with either phenoxy or core-shell rubber (CSR)-MB at various concentrations in order to highlight the impact of the toughening agent on the viscoelasticity and Tg
Summary
For high-performance epoxy resins, thermoplastics represent an interesting alternative to rubber, as they improve the fracture toughness of the system, but potentially its modulus and Tg, depending on the selected thermoplastic [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24] Another promising method for epoxy toughening is the addition of block-copolymers (BCPs) [25,26,27,28,29].
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