Correlation between mechanical stiffness and thermal transport along the solid framework of a uniaxially compressed polyurea aerogel

Weigold, Lena; Reichenauer, Gudrun

doi:10.1016/j.jnoncrysol.2014.09.040

Cited by 17 publications

(21 citation statements)

References 20 publications

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“…The macroscopic material properties depend on the density of the samples and the processing conditions. Specific information about the reactants and synthesis procedure are given in references [27][28][29]. The first sample series consists of six samples (A-F) of different density between 0.040 and 0.530 g/cm 3 that were derived by varying the monomer concentration in the sol solution.…”

Section: Methodsmentioning

confidence: 99%

“…Details with respect to the experimental setups and sample preparation are given in [28] and [29], respectively.…”

Section: Microstructurementioning

confidence: 99%

“…To obtain the heat transfer along the solid framework s , samples were measured in the evacuated state and radiative contribution to the heat transport was subtracted from the experimentally derived data. Details of the experimental setups and evaluation methods are given in [28] and [29], respectively.…”

Section: Thermal Conductivitymentioning

confidence: 99%

“…As the stress-strain-curve of the PUA aerogels does not show clearly a region of linear elasticity [29], the elastic modulus c 11 that is derived from the velocity of a longitudinal ultrasonic wave v l [31], was chosen to characterize the macroscopic elastic modulus of the PUA samples (instead of using an engineering modulus). To calculate the elastic modulus c 11 of aerogels, the void fraction (porosity), the pore gas density gas , the gas pressure p gas and the adiabatic exponent Ä of the pore gas have to be taken into account [31,32]:…”

Section: Elastic Modulusmentioning

confidence: 99%

“…4 By the stepwise compression of a native sample from 10 mm to 1 mm in length a series of 15 measurements was derived. The density for the uniaxially compressed samples was calculated from the density of the native sample and the respective length of the uniaxially compressed sample, neglecting a possibly induced deformational lateral strain [29].…”

Section: Elastic Modulusmentioning

confidence: 99%

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Correlation between the elastic modulus and heat transport along the solid phase in highly porous materials: Theoretical approaches and experimental validation using polyurea aerogels

Weigold

Reichenauer

2015

The Journal of Supercritical Fluids

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Section: Methodsmentioning

confidence: 99%

“…Details with respect to the experimental setups and sample preparation are given in [28] and [29], respectively.…”

Section: Microstructurementioning

confidence: 99%

Section: Thermal Conductivitymentioning

confidence: 99%

Section: Elastic Modulusmentioning

confidence: 99%

Section: Elastic Modulusmentioning

confidence: 99%

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Correlation between the elastic modulus and heat transport along the solid phase in highly porous materials: Theoretical approaches and experimental validation using polyurea aerogels

Weigold

Reichenauer

2015

The Journal of Supercritical Fluids

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Acoustic Properties of Aerogels: Current Status and Prospects

et al. 2022

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Noise pollution has been aptly described as one of the modern plagues. [1] Due to many adverse health effects of loud environments, ranging from sleep disturbances to cardiovascular diseases, reducing the exposure of humans to excess noise is essential to the public health of large populations living in the cities. Regarding sound absorption materials, the optimal choice depends on the intended sound frequency range; solutions of damping high-frequency sound waves rely on totally different absorption mechanism than the solutions for very low-frequency noise. Indoors, the most commonly used sound absorption materials are porous by nature due to their ability to efficiently absorb sound at mid to high frequencies with relatively thin layers. Common porous absorption materials in the market, targeting to over 90% absorption above 350 Hz, are glass and mineral wools and acoustic foams made, e.g., from melamine or polyurethane. Here, we review the acoustic properties of aerogels and demonstrate their high potential to challenge and exceed the absorption properties of the current market standards, whether we talk about the performance in

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Towards the Optimization of Polyurethane Aerogel Properties by Densification: Exploring the Structure–Properties Relationship

Merillas,

García‐González,

Álvarez‐Arenas

et al. 2024

Small Structures

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The aerogel performance for industrial uses can be tailored using several chemical and physical strategies. The effects of a controlled densification on polyurethane aerogels are herein studied by analyzing their textural, mechanical, sound, optical, and thermal insulating properties. The produced aerogels are uniaxially compressed to different strains (30%–80%) analyzing the consequent changes in the structures and, therefore, final properties. As expected, their mechanical stiffness can be significantly increased by compression (until 55‐fold higher elastic modulus for 80%‐strain), while the light transmittance does not noticeably worsen until it is compressed more than 60%. Additionally, the modifications produced in the heat transfer contributions are analyzed, obtaining the optimum balance between density increase and pore size reduction. The minimum thermal conductivity (14.5%‐reduction) is obtained by compressing the aerogel to 50%‐strain, where the increment in the solid conduction is surpassed by the reduction of the radiative and gas contributions. This strategy avoids tedious chemical modifications in the synthesis procedure to control the final structure of the aerogels, leading to the possibility of carefully adapting their structure and properties through a simple method such as densification. Thus, it allows to obtain aerogels for current and on‐demand applications, which is one of the main challenges in the field.

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Correlation between mechanical stiffness and thermal transport along the solid framework of a uniaxially compressed polyurea aerogel

Cited by 17 publications

References 20 publications

Correlation between the elastic modulus and heat transport along the solid phase in highly porous materials: Theoretical approaches and experimental validation using polyurea aerogels

Correlation between the elastic modulus and heat transport along the solid phase in highly porous materials: Theoretical approaches and experimental validation using polyurea aerogels

Acoustic Properties of Aerogels: Current Status and Prospects

Towards the Optimization of Polyurethane Aerogel Properties by Densification: Exploring the Structure–Properties Relationship

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