Epoxy networks toughened by core–Shell particles: Influence of the particle structure and size on the rheological and mechanical properties

Abstract

ABSTRACT:The core-shell particles considered were poly(butyl acrylate) core/epoxy groups functionalizing the poly(methyl methacrylate) shell. Physical and thermomechanical properties of benzyl dimethylamine (BDMA)-catalyzed diglycidyl ether of bisphenol A (DGEBA)/dicyandiamine epoxy networks toughened with core-shell particles were studied. The blends were prepared under well-defined processing conditions. The resulting properties were found to depend on the state of the dispersion of the particles in the prepolymer matrix before crosslinking. These particles were dispersed at different volume fractions in order to vary the interparticle distance. The relationships between the size of the core-shell particles and the level of toughening are reported. Static mechanical tests were performed in tension and compression modes on these core-shell polyepoxy blends. A slight decrease in the Young's modulus and an increase in the ability to plastic deformation were observed. Using linear fracture mechanics (LEFM), an improvement of the fracture properties (K IC ) was measured. By varying the volume fraction of core-shell particles, an optimum toughness improvement was found for an interparticle distance equal to 400 nm (with an average particle size of 600 nm).

Use of Functional (Meth)acrylic Cross‐Linked Polymer Microparticles as Toughening Agents for Epoxy/Diamine Thermosets

“…This is a consequence of their cross‐linked structure. The low solution viscosity can be of high practical interest for processing especially when compared to the much higher viscosity obtained with other toughening agents such as block copolymers or core‐shell particles 15…”

“…Another toughening method consists in incorporating preformed thermoplastic particles, generally in the micron range,11 or core‐shell rubber (CSR) particles 12,13. Although they are not reactive towards the epoxy/amine matrix in general, some functional core‐shells have been used 14,15. In this case, the chemical bonding between the core‐shell particles and the matrix is a key parameter for toughness.…”

“…In this case, the chemical bonding between the core‐shell particles and the matrix is a key parameter for toughness. It has been shown that the state of dispersion of core‐shell particles is another critical parameter for the toughening properties 15,16. First, the core‐shell particles are very difficult to blend homogeneously with the thermoset precursors.…”

Nanostructure Formation in Thermoset/Block Copolymer and Thermoset/Hyperbranched Polymer Blends

“…In those systems, HBP was used as a dispersed phase and did not react with epoxy resins. [17,18]. They determined that the addition of a hydroxyl-terminated HBP to the system would provide ester linkages by reaction of anhydride not only with epoxides but also with hydroxyl groups.…”

Study of matrix micro-cracking in nano clay and acrylic tri-block-copolymer modified epoxy/basalt fiber-reinforced pressure-retaining structures

“…One possible route to enhance ductility of thermosets is by dispersing rubbery phases inside the polymer matrix, i.e. liquid rubbers [7][8][9][10][11][12][13], thermoplastic spheres [14,15], core-shell particles [16][17][18] and nanostructured block-copolymers [19][20][21][22][23].…”