Acoustic Properties of Organic/Inorganic Composite Aerogels

Dong, Winny; Faltens, Tanya; Pantell, Michael; Simon, Diána; Thompson, Travis; Dong, Wayland

doi:10.1557/proc-1188-ll07-02

Cited by 12 publications

(9 citation statements)

References 6 publications

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“…The mechanical characterization techniques for aerogels can be categorized into static (three-point bending and uniaxial compression) or dynamic (ultrasonic, Brillouin scattering, dynamic mechanical analysis) techniques. The elastic properties of aerogels like Young's modulus, Poisson ratio, shear modulus, and internal friction are analyzed using dynamic techniques whereas elastic modulus and rupture strength are determined through static techniques [125][126][127][128]. Single Edge Notched Beam and double cleavage drilled compression tests are also commonly used to characterize the toughness and stress corrosion resistance of aerogels [125,129].…”

Section: Mechanical Analysis Of Aerogelsmentioning

confidence: 99%

Multifunctional Composite Aerogels—As Micropollutant Scavengers

Mertah

James

Zargar

et al. 2021

Inorganic-Organic Composites for Water and Wastewater Treatment

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Composite aerogels are low-density porous material with a high surface area, facilitating their application in wastewater treatment. The surface of these aerogels can be modified based on the ionic charge of the target pollutants. Improved properties like high gas holdup, a low mean free path of diffusion, high mechanical strength, and integrated 3D gel architecture make them an ideal matrix for several environmental applications. This review focuses on carbon, silica, metal-based, and biopolymer composite aerogels toward effluent treatment. The challenges in the synthesis of aerogels using various reduction methods and strategies for surface modification of aerogels having improved water treatment properties are compared. Composite aerogels' application for removing textile dyes, heavy metals, and pesticides, and the oil separation is discussed along with relevant reaction kinetics. The adsorptive and photocatalytic removal of micropollutants by aerogels are also compared. Though several novel composite aerogels have been experimented with in wastewater treatment, the toxicity implications limit their extensive scale application. The toxicity of precursor compounds such as polyacrylonitrile, resorcinol-formaldehyde, phenol, Tetramethyl orthosilicate (TMOS), and leaching of nanoparticles from aerogels are discussed. As a solution to these impediments, bio-aerogels' use and O. Mertah et al.-All authors contributed equally.

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Section: Mechanical Analysis Of Aerogelsmentioning

confidence: 99%

Multifunctional Composite Aerogels—As Micropollutant Scavengers

Mertah

James

Zargar

et al. 2021

Inorganic-Organic Composites for Water and Wastewater Treatment

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“…In the literature, the elastic behaviour is generally tested by ultrasounds measurements [1,9,29,30,50,[51][52][53][54][55][56]. The method often used to determine the velocity of sound in a material is to determine the delay of propagation between the faces of a sample in which a pulse wave propagates.…”

Section: ) Ultrasoundmentioning

confidence: 99%

Techniques for characterizing the mechanical properties of aerogels

Woignier

Primera

Alaoui³

et al. 2019

J Sol-Gel Sci Technol

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In this paper, we present the different characterization techniques used to measure the mechanical properties of silica aerogels. The mechanical behaviour of aerogels is generally described in terms of elastic and fragile materials (such as glasses or ceramics) but also in terms of plastic media in compression testing. Because of these very different mechanical behaviors, several types of characterization techniques are proposed in the literature. We first describe the dynamic characterization techniques such as ultrasounds, Brillouin scattering, dynamic mechanical analysis (DMA) to measure the elastic properties: Young's modulus (E) , shear modulus (G), poisson ratio (υ) but also attenuation and internal friction. Thanks to "static" techniques such as three-point bending, uniaxial compression, compression we also access to the elastic modulus (E) and to the rupture strength (σ). The experimental results show that the value of the elastic and fracture moduli measured is several orders of magnitude lower than that of a material without porosity. With regard to the brittleness characteristics, Weibull's analysis is used to show the statistical nature of the fracture resistance. We also present the SENB (single edge notched beam technique) technique to characterize toughness (K1C) and the stress corrosion mechanisms, which are studied in ambient conditions and temperature by the double-cleavage drilled compression experiment (DCDC). In the last part of the paper, we show how, during the isostatic compression test, aerogels behave like plastic materials.The data allow calculating the bulk modulus (K), the amplitude of the plastic deformation and the yield strength (σel), which is the boundary between the elastic and plastic domains. These different techniques allow understanding which parameters influence the overall mechanical behavior of aerogels, such as pore volume, but also pore size, internal connectivity and silanol bounds content. It is shown that pore size plays a very important role; pores can be considered as flaws in the terms of fracture mechanics.

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“…The mechanical properties such the Young modulus can also affect the absorption coefficient. By reducing Young's modulus in porous materials, the absorption coefficient can be enhanced [29].…”

Section: Determination Of Morphologymentioning

confidence: 99%

Improving the Sound Absorption Properties of Flexible Polyurethane (PU) Foam using Nanofibers and Nanoparticles

Hajizadeh¹,

Khavanin²,

Barmar³

et al. 2019

Sound&Vibration

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Polyurethane foam as the most well-known absorbent materials has a suitable absorption coefficient only within a limited frequency range. The aim of this study was to improve the sound absorption coefficient of flexible polyurethane (PU) foam within the range of various frequencies using clay nanoparticles, polyacrylonitrile nanofibers, and polyvinylidene fluoride nanofibers. The response surface method was used to determine the effect of addition of nanofibers of PAN and PVDF, addition of clay nanoparticles, absorbent thickness, and air gap on the sound absorption coefficient of flexible polyurethane foam (PU) across different frequency ranges. The absorption coefficient of the samples was measured using Impedance Tubes device. Nano clay at low thicknesses as well as polyacrylonitrile nanofibers and polyvinyl fluoride nanofibers at higher thicknesses had a greater positive effect on absorption coefficient. The mean sound absorption coefficient in the composite with the highest absorption coefficient at middle and high frequencies was 0.798 and 0.75, respectively. In comparison with pure polyurethane foam with the same thickness and air gap, these values were 2.22 times at the middle frequencies and 1.47 times at high frequencies, respectively. Surface porosity rose with increasing nano clay, but decreased with increasing polyacrylonitrile nanofibers and polyvinyl fluoride nanofibers. The results indicated that the absorption coefficient was elevated with increasing the thickness and air gap. This study suggests that the use of a combination of nanoparticles and nanofibers can enhance the acoustic properties of flexible polyurethane foam.

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Acoustic Properties of Organic/Inorganic Composite Aerogels

Cited by 12 publications

References 6 publications

Multifunctional Composite Aerogels—As Micropollutant Scavengers

Multifunctional Composite Aerogels—As Micropollutant Scavengers

Techniques for characterizing the mechanical properties of aerogels

Improving the Sound Absorption Properties of Flexible Polyurethane (PU) Foam using Nanofibers and Nanoparticles

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