Self‐Healing, Robust, and Stretchable Electrode by Direct Printing on Dynamic Polyurea Surface at Slightly Elevated Temperature

Among many applications, elevated-temperature cured epoxy resins are widely used for high-performance applications especially for structural adhesive and as a matrix for structural composites. This is due to their superior chemical and mechanical properties. The thermosetting nature of epoxy produces a highly cross-linked polymer network during the curing process where the resulting material exhibited excellent properties. However, due to this cross-linked molecular structure, epoxies are also known to be brittle, and once a crack initiated in the material, it is difficult to arrest the crack propagation. Earlier research found that the inclusion of encapsulated healing agents is able to introduce self-healing ability to the room-temperature cured epoxies. The current study investigated the self-healing behaviour of an elevated-temperature cured epoxy, which incorporated the dual-capsule system loaded with diglycidyl-ether of bisphenol-A (DGEBA) resin and mercaptan. The microcapsules were prepared by the in-situ polymerisation method while the fracture toughness and the self-healing capability of the tapered-double-cantilever-beam (TDCB) epoxy specimens were measured under Mode-I fracture toughness testing. We investigated the effect of temperature on viscosity of the healing agents and how these values influence the formation of uniform healing on the fracture surfaces. It was found that incorporation of the dual-capsule self-healing system onto an elevated-temperature cured epoxy slightly changed the fracture toughness of the epoxy as indicated by the Mode-I testing. In the case of thermal healing at 70°C, the self-healing epoxy exhibited a recovery of up to 111% of its original fracture toughness, where a uniform spreading of the healant was observed. The excellent healing behaviour is attributed to the lower viscosity of the healant at higher temperature and the higher glass transition temperature ( Tg) of the produced healant film. The DSC analysis confirmed that the healing process was not contributed by the post-curing of the host epoxy.

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Self-healing epoxy with ultrafast and heat-resistant healing system processable at elevated temperature

Composites Science and Technology ◽

10.1016/j.compscitech.2014.08.028 ◽

2014 ◽

Vol 104 ◽

pp. 40-46 ◽

Cited By ~ 19

Author(s):

Xiao Ji Ye ◽

Yi Xi Song ◽

Yong Zhu ◽

Gui Cheng Yang ◽

Min Zhi Rong ◽

...

Keyword(s):

Elevated Temperature ◽

Self Healing ◽

Heat Resistant ◽

Healing System

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Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011043x ◽

1978 ◽

Vol 36 (1) ◽

pp. 658-659

Author(s):

G.J.C. Carpenter

Keyword(s):

Elevated Temperature ◽

Strain Field ◽

Zirconium Hydride ◽

Zirconium Atom ◽

Atom Diffusion ◽

Solvus Temperature ◽

Hexagonal Close Packed ◽

Partial Dislocations ◽

The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

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Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104819 ◽

1988 ◽

Vol 46 ◽

pp. 550-551

Author(s):

R. E. Franck ◽

J. A. Hawk ◽

G. J. Shiflet

Keyword(s):

High Temperature ◽

Elevated Temperature ◽

Grain Growth ◽

Volume Fraction ◽

Microstructural Characterization ◽

Second Phase ◽

Microstructural Stability ◽

Elevated Temperature Strength ◽

Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

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Autonomous self-healing polyisoprene elastomers with high modulus and good toughness based on the synergy of dynamic ionic crosslinks and highly disordered crystals

Polymer Chemistry ◽

10.1039/d0py01034k ◽

2020 ◽

Vol 11 (41) ◽

pp. 6549-6558

Author(s):

Yohei Miwa ◽

Mayu Yamada ◽

Yu Shinke ◽

Shoichi Kutsumizu

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Self Healing ◽

High Modulus ◽

Disordered Crystals ◽

Ionic Crosslinks

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

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