The effect of capsulated nanosilica-epoxy healing agents on the self-healing ability of glass fibers-epoxy composites under mechanical loading

Abstract

In this study, the effect of using an epoxy healing agent containing silica nanoparticles instead of the neat epoxy healing agent on the self-healing ability of glass fibers/epoxy composites under the flexural, tensile and shear loadings was assessed. For doing this, in the first step, the silica nanoparticles (0, 1, 2 and, 3 wt.%) were dispersed into the ethyl acetate/epoxy healing agent. Then, these mixtures were encapsulated with the urea-formaldehyde polymer by an in-situ polymerization method. Finally, the glass fibers/epoxy composite containing 14 wt.% microcapsules along with 2 wt.% NiCl2(imidazole)4 catalyst were fabricated. To understand how the mechanical-healing behaviors of these composites under the various mechanical loads, these composites were destructed with a quasi-static penetration test for the creation of delamination damage. The healing process was done by the thermal activation method. The obtained results showed that the highest healing efficiency under the flexural, tensile and shear loads belonged to the composite containing 1 wt.% nanosilica into the healing agent, which were 89.8, 87.8, and 156.8%, respectively. The hackles of microcapsules, reduction in the thickness of microcapsules, formation of nanocomposite healing shell and the agglomeration of silica nanoparticles on the healed area were the influence factors on the healing ability of these composites. This work can give a view for healing the microcracks into composite structures by nanocomposite healing agents, which have the higher healing ability and better performance under mechanical loads than conventional healing agents.

Ultrafast Self-Healing Fiber/Matrix Composite with Single-Component Microcapsules Loaded with Cationic Catalyst

“…Furthermore, the synergistic effect of encapsulated nanosilica–epoxy healing agents on the self-healing behavior of epoxy composites has been studied. Taking the advantage of the damage mode change of composites, the self-healing efficiency was further improved. , However, the aforementioned repairing systems were either time-consuming (48 h for the self-healing process) or required additional energy stimulation (over 100 °C). The main reason for the low healing rate was the slow ring-opening polymerization reaction of the epoxy resin with the curing agent.…”

“…Because the type of epoxy agent was the same as that used to build the matrix, the miscibility between the healing agent and the matrix was guaranteed. 25,26 Until now, extensive studies on two-component epoxy-containing repair systems for selfhealing, such as epoxy/amine, 27 epoxy/mercaptan, 28 and epoxy/latent curing agents, 29 have been conducted to improve healing efficiency. Furthermore, the synergistic effect of encapsulated nanosilica−epoxy healing agents on the selfhealing behavior of epoxy composites has been studied.…”

Self‐healing polymers containing nanomaterials for biomedical engineering applications: A review

“…In extrinsic self-healing, a healing agent has to be added to the matrix of the material in the form of microcapsule structures. [6][7][8] When microcracks propagate through the matrix, the healing agent is released from ruptured microcapsules. [9][10][11] In intrinsic self-healing, [12][13][14] materials can self-heal on their own based on reversible dynamic covalent 15,16 or noncovalent bonds, host-guest interaction, [17][18][19] and metallo/ ligand complexation 20 without the need to add any healing agents.…”

“…Self‐ healing materials can be classified into extrinsic and intrinsic types. In extrinsic self‐healing, a healing agent has to be added to the matrix of the material in the form of microcapsule structures 6–8 . When microcracks propagate through the matrix, the healing agent is released from ruptured microcapsules 9–11 .…”

Evaluation of interlaminar shear strength of co-cured fiber-reinforced fabric composite structures by lap joint method

“…V-notched shear method [12,13] and short beam shear (SBS) method [14][15][16][17][18][19][20][21][22][23] are commonly used to measure ILSS of FRC. The V-noted specimen is manufactured by thickly stacking FRC and then applying notches located centrally according to the shear direction to be measured.…”