Damping Properties of Nanoporous Carbon‐Cyclohexane Mixtures

Abstract

Using liquids in mounting stages, packaging layers, helmets and healthcare pads, etc. has been a common engineering practice. [1] Usually, a "liquid damper" contains a sealing layer and a liquid core, which can nearly perfectly fit with the target to be protected. As a result, the contact area is maximized and thus the contact pressure is lowered. Damages associated with interface mismatches that commonly exist in solid systems, especially in systems of changing configurations, are also largely reduced. Additionally, the internal friction caused by liquid motions can considerably change the load and deformation distribution profiles. For instance, shear thickening liquids exhibit attractive mechanical characteristics when subjected to high-strain-rate shear loadings, and therefore can be used in protection layers, soldier armors, among others. [2] A major problem of most of the liquid systems is that the compressibility of the liquids is poor, and the loading-unloading processes are reversible. Consequently, under a compressive loading, the energy absorption of the liquid phase is negligible. While this is not an issue for quasistatic loadings, for dynamics loadings the transmitted highstress waves can cause serious damages, e.g. blast-lung problems. [3,4] In order to improve the energy dissipation capacities of liquids, the technique of nanoporous-admixture functionalization has been recently developed. [5][6][7][8][9] By immersing a lyophobic nanoporous material in a liquid, as the pressure is increased so that the capillary effect is overcome, the liquid can be compressed into the nanopores, accompanied by the large increase in liquid-solid contact area. Since the specific area of a nanoporous material is typically millions of times larger than in bulk materials, the associated specific free energy increase can be as high as 10-100 J/g; that is, as the energy converted from the quasi-hydrostatic pressure to the solid-liquid interfacial tension can be regarded as being dissipated, the energy absorption efficiency of the nanoporous liquid is ultrahigh. However, the previous studies were mainly focused on nanoporous silicas and zeolite-like materials, which are relatively cost inefficient, especially for largescale structures such as damping foundations. It would be desirable if more available materials, such as nanoporous carbons, can be used for energy absorption applications. Moreover, in the previously developed systems, the system recoverability was usually quite poor; i.e. after the first loadingunloading cycle, since most of the confined liquid could not defiltrate from the nanopores, the energy absorption capacity became much smaller at the second loading. While a few techniques, such as thermal treatment and recovery agent addition have been developed, [10,11] the system performance under cyclic loadings was still far from satisfactory. Results and DiscussionIn the current study, we investigated two J. B. Baker nanoporous carbons: E-343 and E-345 using the experimental setup depicted in Figure 1. The res...

Deformation of a nanoporous silica under compressive loading

“…[33][34][35][36] Even if liquids of larger surface tensions are utilized, the maximum energy absorption efficiency is only about 100 J/g. 37,38 The high energy absorption performance of the nanoporous silica gel should be attributed to the small nanopore size, the relatively large porosity, as well as the high network strength.…”

Infiltration of liquid metals in a nanoporous carbon

“…They are also much more cost-efficient, which is critical to large-scale engineering applications, such as liquid foundations, protection layers for highway bridges and buildings, etc. However, although at macroscopic length scale it was reported that a carbon material may be hydrophobic [13,14], in a nano-environment, pressureinduced wetting can be difficult [15]. For instance, in a SEM study, Rossi et al [16] argued that carbon nanotubes were wettable in water, which was in agreement with the conclusion of Dujardin et al [17] that carbon nanotubes can be wetted by liquids with surface tensions smaller than 130-170 mJ/m 2 .…”

Understanding Energy Absorption Behaviors of Nanoporous Materials

“…where ξ 1 and ξ 2 are the free energies of state 1 and state 2, respectively; P is the applied pressure, V is the volume of the water; γ is the excess solid-liquid interfacial tension; A is the associate solid-liquid interface area; Δμ is the specific free energy difference; and K is the bulk modulus of the gel, which is around 0.1 GPa. 12 The 2 nd , 3 rd , 4 th , and 5 th terms at the RHS of Eq. (F-1) capture the external work, the solid-liquid interaction, the confinement effect of the PIMA-Na gel, and the strain energy, respectively.…”

“…If the cell wall size is large, the first-order mode is most energetically favorable. 12 Recent research has shown that if soft joints are installed, they would trigger higher-order buckling modes under a relatively low pressure, and thus both temporal and spatial characteristics of buckling patterns are adjusted. 13 Decreasing the cell size can be of a similar effect.…”