Abstract:The crack growth dynamics of the carbon-black (CB) filled elastomers is studied experimentally and analyzed while focusing on both kinetics and crack tip profiles. The CB amounts are varied to change the mechanical properties of the elastomers. Static crack growth measurements simultaneously reveal the discontinuous-like transition of the crack growth rate v between the "slow mode" (v≈10^{-5}-10^{-3} m/s) and "fast mode" (v≈10^{-1}-10^{2} m/s) in a narrow range of the input tearing energy Γ and the accompanyin… Show more
“…8 account very well for the experimental data and yield numerical values for δ between 0.017 and 0.2 mm, and for a between 0.42 and 0.76 mm −1 . This type of profile has already been observed experimentally in elastomers and permanent gels Deegan et al (2001); Livne et al (2008); Goldman et al (2012); Morishita et al (2016). Similarly to previous works, we find that overall δ increases as the propagation velocity of the crack increases ( fig.…”
Section: Crack Opening Profilessupporting
confidence: 90%
“…δ cannot be regarded as a characteristic length of a process zone, and argue indirectly that δ is related to finite elasticity. More recently, a correlation has been experimentally shown between δ and the hyperelasticity measured independently for elastomers filled with various amounts of carbon black Morishita et al (2016). Our data allows us to check for a direct correlation between the shape of the opening profile and the sample non linear viscoelasticity.…”
SynopsisWe study the fracture of reversible double transient networks, constituted of water suspensions of entangled surfactant wormlike micelles reversibly linked by various amounts of telechelic polymers. We provide a state diagram that delineates the regime of fracture without necking of the filament from the regime where no fracture or break-up has been observed. We show that filaments fracture when stretched at a rate larger than the inverse of the slowest relaxation time of the networks. We quantitatively demonstrate that dissipation processes are not relevant in our experimental conditions and that, depending on the density of nodes in the networks, fracture occurs in the linear viscoelastic regime or in a non-linear regime. In addition, analysis of the crack opening profiles indicates deviations from a parabolic shape close to the crack tip for weakly connected networks. We demonstrate a direct correlation between the amplitude of the deviation from the parabolic shape and the amount of non linear viscoelasticity.
“…8 account very well for the experimental data and yield numerical values for δ between 0.017 and 0.2 mm, and for a between 0.42 and 0.76 mm −1 . This type of profile has already been observed experimentally in elastomers and permanent gels Deegan et al (2001); Livne et al (2008); Goldman et al (2012); Morishita et al (2016). Similarly to previous works, we find that overall δ increases as the propagation velocity of the crack increases ( fig.…”
Section: Crack Opening Profilessupporting
confidence: 90%
“…δ cannot be regarded as a characteristic length of a process zone, and argue indirectly that δ is related to finite elasticity. More recently, a correlation has been experimentally shown between δ and the hyperelasticity measured independently for elastomers filled with various amounts of carbon black Morishita et al (2016). Our data allows us to check for a direct correlation between the shape of the opening profile and the sample non linear viscoelasticity.…”
SynopsisWe study the fracture of reversible double transient networks, constituted of water suspensions of entangled surfactant wormlike micelles reversibly linked by various amounts of telechelic polymers. We provide a state diagram that delineates the regime of fracture without necking of the filament from the regime where no fracture or break-up has been observed. We show that filaments fracture when stretched at a rate larger than the inverse of the slowest relaxation time of the networks. We quantitatively demonstrate that dissipation processes are not relevant in our experimental conditions and that, depending on the density of nodes in the networks, fracture occurs in the linear viscoelastic regime or in a non-linear regime. In addition, analysis of the crack opening profiles indicates deviations from a parabolic shape close to the crack tip for weakly connected networks. We demonstrate a direct correlation between the amplitude of the deviation from the parabolic shape and the amount of non linear viscoelasticity.
“…Their numerical model takes into account nonlinear viscoelasticity introducing 30 material parameters, by quantitatively fitting the result of the experiment in ref. 17. Although they qualitatively reproduced jumps, their simulation result of the G - V plot shown in Fig.…”
Section: Discussionmentioning
confidence: 87%
“…(ii) The experiment shown in Fig. 1e
14 and many other experiments 15–17 indicate that the G - V plots exhibit an intriguing structure for elastomers: the velocity V jumps at a critical value G = G
c , causing a transition from the slow-velocity ( mm/s) to fast-velocity ( mm/s) regime. This G - V structure reveals that toughness is achieved by increasing the critical value G
c because such an increase reduces the risk of a velocity jump, which can trigger catastrophic failure.Figure 1Velocity jump observed in the fixed-grip crack propagation.…”
Needs to impart appropriate elasticity and high toughness to viscoelastic polymer materials are ubiquitous in industries such as concerning automobiles and medical devices. One of the major problems to overcome for toughening is catastrophic failure linked to a velocity jump, i.e., a sharp transition in the velocity of crack propagation occurred in a narrow range of the applied load. However, its physical origin has remained an enigma despite previous studies over 60 years. Here, we propose an exactly solvable model that exhibits the velocity jump incorporating linear viscoelasticity with a cutoff length for a continuum description. With the exact solution, we elucidate the physical origin of the velocity jump: it emerges from a dynamic glass transition in the vicinity of the propagating crack tip. We further quantify the velocity jump together with slow- and fast-velocity regimes of crack propagation, which would stimulate the development of tough polymer materials.
Recently, many tough and self-healing hydrogels have been developed based on physical bonds as reversible sacrificial bonds. As breaking and reforming of physical bonds are time-dependent, these hydrogels are viscoelastic and the deformation rate and temperature pronouncedly influence their fracture behavior. Using a polyampholyte hydrogel as a model system, we observed that the time-temperature superposition principle is obeyed not only for the small strain rheology, but also for the large strain 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
