Fracture Testing of a Self-Healing Polymer Composite

Brown, Eric N.; Sottos, Nancy R.; White, Scott R.

doi:10.1177/001448502321548193

Cited by 146 publications

(216 citation statements)

References 74 publications

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“…For the TDCB sample geometry in Fig. 1, α = 11.2x10 3 m -3/2 was determined experimentally [17]. A constant range of Mode-I stress intensity factor ∆K I was achieved by applying a constant range of load ∆P, independent of crack length.…”

Section: Mechanical Testingmentioning

confidence: 99%

“…In addition to providing an efficient mechanism for self-healing [16][17][18], the presence of liquid-filled microcapsules increased the virgin monotonic-fracture toughness of epoxy by up to 127% [15,17]. The increased toughening was correlated with a change in the fracture plane morphology from mirror-like to hackle markings with subsurface microcracking.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue crack propagation in microcapsule-toughened epoxy

2006

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The addition of liquid-filled urea-formaldehyde (UF) microcapsules to an epoxy matrix leads to significant reduction in fatigue crack growth rate and corresponding increase in fatigue life. Mode-I fatigue crack propagation is measured using a tapered doublecantilever beam (TDCB) specimen for a range of microcapsule concentrations and sizes: 0, 5, 10, and 20% by weight and 50, 180, and 460 µm diameter. Cyclic crack growth in both the neat epoxy and epoxy filled with microcapsules obeys the Paris power law. Above a transition value of the applied stress intensity factor ∆K T , which corresponds to loading conditions where the size of the plastic zone approaches the size of the embedded microcapsules, the Paris law exponent decreases with increasing content of microcapsules, ranging from 9.7 for neat epoxy to approximately 4.5 for concentrations above 10 wt% microcapsules. Improved resistance to fatigue crack propagation, indicated by both the decreased crack growth rates and increased cyclic stress intensity for the onset of unstable fatigue-crack growth, is attributed to toughening mechanisms induced by the embedded microcapsules as well as crack shielding due to the release of fluid as the capsules are ruptured. In addition to increasing the inherent fatigue life of epoxy, embedded microcapsules filled with an appropriate healing agent provide a potential mechanism for self-healing of fatigue damage.

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Section: Mechanical Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatigue crack propagation in microcapsule-toughened epoxy

2006

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“…TDCB specimens with groove length of 55 mm [20,21] were cast from the stoichiometric mixture of 100 parts EPON 828, 80 parts curing agent MHHPA and 5 parts accelerant BF 3 !DMA. The compound was firstly degassed, and then poured into a preheated closed silicone rubber mold and cured at 50°C for 60 h and 70°C for 12 h. SbF 5 !HOC 2 H 5 /HOC 2 H 5 (concentration of SbF 5 = 5 wt%), the hardener component of the healing agent, was prepared by the method mentioned in ref.…”

Section: Specimen Preparationmentioning

confidence: 99%

Fatigue life extension of epoxy materials using ultrafast epoxy-SbF5 healing system introduced by manual infiltration

Ye¹,

Zhu²,

Yuan³

et al. 2015

Express Polym. Lett.

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Abstract. The present paper is devoted to the verification of the capability of epoxy-SbF 5 system as a healing chemistry for rapidly retarding and/or arresting fatigue cracks in epoxy materials at room temperature. Owing to the very fast curing speed of epoxy catalyzed by SbF 5 , epoxy monomer and the hardener (ethanol solution of SbF 5 -ethanol complex) are successively infiltrated into the fracture plane under cyclic loading during the tension-tension fatigue test. As a result, the mechanisms including hydrodynamic pressure crack tip shielding, polymeric wedge and adhesive bonding of the healing agent are revealed. It is found that the healing agent forms solidified wedge at the crack tip within 20 s after start of polymerization of the epoxy monomer, so that the highest healing effect is offered at the moment. The epoxy-SbF 5 system proves to be effective in rapidly obstructing fatigue crack propagation (despite that its cured version has lower fracture toughness than the matrix), and satisfies the requirement of constructing fast self-healing polymeric materials.

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“…Crack healing efficiency, η, (defined as the ability to recover fracture toughness) was evaluated for the sample cured up to 170 °C using a tapered double-cantilever beam (TDCB) [23,38] geometry. The healing efficiency η, calculated as the ratio of critical fracture loads for the healed and virgin samples, is obtained from data shown in Figure 8 where we report the Load-Displacement curves for a sample with 5% of Hoveyda-Grubbs I Catalyst and 20% of microcapsules (ENB+DCPD) filled, cured up to 170 °C.…”

Section: Healing Efficiency Of the Self-healing Samplementioning

confidence: 99%

“…The challenge facing materials scientists is to assure these systems must be able to stem fatigue damage and preserve their integrity, increase their life span, reduce maintenance costs and provide safety during use. A lot of strategies were formulated up to now in the development of self-healing materials [5,[16][17][18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%