Tuning membrane content of sound absorbing cellular foams: Fabrication, experimental evidence and multiscale numerical simulations

Trinh, Van Hai; Langlois, Vincent; Guilleminot, Johann; Perrot, Camille; Khidas, Yacine; Pitois, Olivier

doi:10.1016/j.matdes.2018.11.023

Cited by 47 publications

(35 citation statements)

References 35 publications

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“…The eects of membrane on acoustical properties are now the subject of active research [3,811]. It has been shown that closed membranes can increase the eective density of foam [8] and therefore, in agreement with the work of Jonhson et al [1], the foam tortuosity α ∞ [10]. Moreover, closed membranes imply some percolation eects at the mesoscale which can drastically reduce the foam permeability K as shown in [9].…”

Section: Introductionmentioning

confidence: 84%

“…We are not aware of any experimental setup able to produce well-dened (geometrically) polymeric structures having closed and open pores of dierent ratios. Milliuidic techniques were, however, employed to generate monodisperse foams with various membrane contents [10]; (geometrically) characterized according to the proportions of closed and open windows and aperture size. While tortuosity estimates were reported using acoustical measurements [28] by Trinh et al [10], the acoustical method failed to provide tortuosity results when the membrane content was too high.…”

Section: Discussionmentioning

confidence: 99%

“…Milliuidic techniques were, however, employed to generate monodisperse foams with various membrane contents [10]; (geometrically) characterized according to the proportions of closed and open windows and aperture size. While tortuosity estimates were reported using acoustical measurements [28] by Trinh et al [10], the acoustical method failed to provide tortuosity results when the membrane content was too high. This suggests that the acoustical method is not appropriate for the characterization of foam having a large proportion of fully closed membranes and/or very low membrane aperture sizes due to the low amplitude of signal transmitted through the sample at the third microphone and the high values of the viscoinertial frequency (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…As shown in Fig. 6, a periodic unit cell (PUC) of characteristic size D b is used to represent the pore structure in foam samples [10,25]. The number of pores, N p , contained within the unit cell is equal to 2.…”

Section: Ordered Kelvin Foammentioning

confidence: 99%

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Electrical conductivity and tortuosity of solid foam: Effect of pore connections

2019

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Numerical and analytical methods at both micro-and mesoscales are used to study how the electrical resistivity and the high frequency tortuosity of solid foam are modied by the presence of membranes that partially or totally close the cell windows connecting neighbor pores. Finite element method (FEM) simulations are performed on two pores connected by a single-holed membrane and on well-ordered Kelvin foam. For two pores connected by a single-holed membrane, we show that the equation for pore access resistance obtained by Sahu and Zwolak (Phys. Rev. E 98, 012404, 2018) can predict, after a few modications, the electrical resistivity at the membrane scale for a large range of membrane apertures. In the second part, considering these analytical results, we build a pore-network model by using two kinds of conductances at the pore scale -inter-pore conductance and intra-pore conductance. Local inter-pore resistances govern foam electrical conductivity at small membrane aperture size, but when the membrane aperture has the same order of magnitude as the pore size, the intra-pore resistances are no longer negligible. An important success of this pore-network model is that it can be used to study the eects of percolation on the foam electrical conductivity by using pore-network simulations on larger samples containing a few thousands of pores and having dierent proportions of closed membrane randomly distributed over the sample.The tortuosity is found to be drastically larger than one in foam containing membranes with small apertures or a signicant fraction of closed membranes.

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Section: Introductionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Ordered Kelvin Foammentioning

confidence: 99%

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Electrical conductivity and tortuosity of solid foam: Effect of pore connections

2019

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“…the way the solid matrix is distributed at the local scale. To this respect, the size of pores and apertures connecting the pores are crucial morphological parameters to control acoustics [3,4].…”

Section: Introductionmentioning

confidence: 99%

A physical approach towards controlling the microstructure of metakaolin-based geopolymer foams

Kaddami

Pitois

2019

Cement and Concrete Research

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Geopolymer foams are promising sustainable lightweight materials combining insulation efficiency with interesting mechanical and fire resistance properties. Controlling their pore size remains challenging because intrinsic foam aging processes act before hardening. We highlight a physical approach to counteracting aging processes in fresh geopolymer foams and to maintaining the pore morphology that has been set initially by mixing metakaolin suspension with precursor aqueous foam. More precisely, it is shown that arrest of foam aging can be achieved if solid particle concentration in the suspension is larger than a critical value which is proved to depend on both bubble size and gas volume fraction. This behavior is understood through the jamming transition occurring for the metakaolin suspension when confined in the foam network, providing significant solid elasticity against bubble motions. The general significance of the reported result makes it useful, as a complement to chemical formulation, for designing morphology-controlled geopolymer foams.

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Scalable Fabrication of Microcellular Open‐Cell Polymer Foams

2021

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Open‐cell foams are foams with porous, interconnected cellular structure. This unique structure has given open‐cell foams the versatility to be used in different types of applications including acoustics, filtration, membranes, and bioscaffolds. Conventional open‐cell polymer foams comprise mainly thermosetting and/or crosslinked materials; such materials are difficult to process and have limited end‐product recyclability. This article presents a commercially viable molding process to fabricate open‐cell foams using noncrosslinked thermoplastic polypropylene (PP). Highly open‐cell and/or reticulated structures at an open‐cell content of 84% are attained. The strategies employed in molding of PP foam with high open‐cell degree include: 1) use of mold‐opening method to achieve high void fractions; 2) reduction of cell‐wall thickness through increasing the cell densities via controlled crystallization; and 3) use of low viscosity or low melt‐strength polymer resins to promote cell‐wall opening. The molding process proposed may be extended to other semicrystalline thermoplastic materials for fabricating recyclable open‐cell foams.

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Tuning membrane content of sound absorbing cellular foams: Fabrication, experimental evidence and multiscale numerical simulations

Cited by 47 publications

References 35 publications

Electrical conductivity and tortuosity of solid foam: Effect of pore connections

Electrical conductivity and tortuosity of solid foam: Effect of pore connections

A physical approach towards controlling the microstructure of metakaolin-based geopolymer foams

Scalable Fabrication of Microcellular Open‐Cell Polymer Foams

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