Polypropylene/Silica Aerogel Composite Incorporating a Conformal Coating of Methyltrimethoxysilane-Based Aerogel

2019 ◽  
Vol 19 (3) ◽  
pp. 1376-1381 ◽  
Author(s):  
Haryeong Choi ◽  
Vinayak G Parale ◽  
Kyu-Yeon Lee ◽  
Ha-Yoon Nah ◽  
Zied Driss ◽  
...  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xinxin Zhang ◽  
Xiaoze Du

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.


2021 ◽  
Vol 13 (9) ◽  
pp. 1820-1824
Author(s):  
Jian-Chun Huo ◽  
Hai-Xia Yang ◽  
Yuan Ma ◽  
Jie Bai

Natural cotton fiber used for reinforcement is low-cost, environmentally friendly, good flexibility and easy to obtain. In this study, a new cotton fiber/silica aerogel composite was developed by sol–gel method via freezedrying. The obtained composite has excellent flexibility and can be restored to its original state after bending for 180° without obvious cracks. After 20 cycles continuous compression, the total unrecoverable strain loss is only 20% under strain of 60%. The composite also shows very prominent hydrophobicity, and the contact angle with water reaches 145 degrees. It has strong adsorption capacity for organic reagents and oil, with adsorption ratios of 500% and 600%, respectively. In addition, the composite has a low thermal conductivity of 0.038 W/(m·K) at room temperature. The obtained composite exhibits considerable promise in oil-water separation and thermal insulation.


2018 ◽  
Vol 15 (6/7) ◽  
pp. 587
Author(s):  
Kyu Yeon Lee ◽  
Ha Yoon Nah ◽  
Haryeong Choi ◽  
Vinayak G. Parale ◽  
Hyung Ho Park

2016 ◽  
Vol 128 ◽  
pp. 111-118 ◽  
Author(s):  
Roberto Garay Martinez ◽  
Eunate Goiti ◽  
Gudrun Reichenauer ◽  
Shanyu Zhao ◽  
Matthias Koebel ◽  
...  

Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xiaoze Du ◽  
Xinxin Zhang

This paper presented theoretical and experimental study on gaseous conductivity of silica aerogel and it’s composite insulation materials. The samples of silica aerogel, xonotlite-type calcium silicate, xonotlite-aerogel composite and ceramic fibre-aerogel composite insulation materials were prepared firstly. The gaseous conductivities of the prepared samples were measured from 0.045 Pa to atmospheric pressure with the transient hot-strip (THS) method. The gaseous conductivity expressions based on the kinetic theory were then compared with the experimental results. It is shown that both the gaseous conductivity of xonotlite-type calcium silicate and silica aerogel decreases significantly with the drop of pressure. The gaseous conductivity of xonotlite-type calcium silicate reaches to zero at about 100 Pa and the gaseous conductivity of silica aerogel reaches to zero at about 104 Pa. The theoretical gaseous conductivity expressions match well with the experimental results of xonotlite-type calcium silicate and silica aerogel respectively, but do not match with the experimental results for the composite insulation materials. It indicates that the aerogel does not fill the two kinds of composite insulation materials entirely, and some micro level pores still exist in them.


2019 ◽  
Vol 53 (28-30) ◽  
pp. 4117-4124
Author(s):  
Xinli Ye ◽  
Zhaofeng Chen ◽  
Sufen Ai ◽  
Junxiong Zhang ◽  
Bin Hou ◽  
...  

A novel structure-controllable reticulated silicon carbide (SiC) skeleton-reinforced silica aerogel composites (SiC/aerogel) were fabricated successfully by template method. Three-dimensional SiC skeletons prepared by different deposition time were prepared via the chemical vapor deposition technology, and then the silica aerogel was induced by the sol–gel process. The test results showed that the mechanical properties increased and thermal conductivities decreased remarkably after impregnating reticulated SiC skeleton with silica aerogel. The SiC/aerogel-24 possessed the highest compressive strength of 0.82 MPa with the thermal conductivity of 0.1597 W/(m·K) at 600℃, while the SiC/aerogel-12 exhibited the lowest thermal conductivity of 0.1244 W/(m·K) and its compressive strength was 0.64 MPa. The present work reported a novel method to manufacture the structure-controllable reticulated SiC aerogel composite which could be used as a high-temperature super-thermal insulation material for the potential applications.


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