Role of Urea in the Preparation of Highly Porous Nanocomposite Aerogels

Langmuir ◽  
2007 ◽  
Vol 23 (7) ◽  
pp. 3509-3512 ◽  
Author(s):  
Maria F. Casula ◽  
Danilo Loche ◽  
Sergio Marras ◽  
Giorgio Paschina ◽  
Anna Corrias
Keyword(s):  
Porous Nanocomposite ◽  
Highly Porous

Study of the Water-Glass Role in the Foam Glass Synthesis Using Glycerol Foaming Agent

2021 ◽  
Vol 316 ◽  
pp. 153-158
Author(s):  
Boris M. Goltsman ◽  
Lyubov A. Yatsenko ◽  
Natalia S. Goltsman
Keyword(s):  
Porous Structure ◽  
Structure Formation ◽  
Water Glass ◽  
Glass Batch ◽  
Foam Glass ◽  
Foaming Agent ◽  
Additive Type ◽  
Highly Porous ◽  
Material Porosity

The article discusses the peculiarities of the "water-glass – glycerol" foaming mixture components interaction during foam glass synthesis. The important role of the foaming additive type in the foam glass porous structure formation was described, the main foaming substances were listed. The obtaining and researching technology of the samples was described, the compositions of the initial batches using the "water-glass – glycerol" mixture were developed. It was shown that a material with a highly porous structure and density below 500 kg/m3 can be obtained only with the combined introduction of water-glass and glycerol. In this case, mixtures with a predominance of water-glass in the foaming mixture possess optimal properties. Using DSC, it was shown that the addition of water-glass to the mixture completely eliminates the evaporation of glycerol at lower temperatures and intensifies its combustion at higher temperatures. Thus, the addition of water-glass to the glycerol-based foam glass batch allows glycerol to be saved up to higher temperatures that increases the resulting material porosity.

Control of Failure Evolution in 3D Cellular Woven Composite Systems

2000 ◽  
Author(s):  
Jared N. Baucom ◽  
Mohammed A. Zikry ◽  
Yiping Qiu
Keyword(s):  
Areal Density ◽  
Textile Composites ◽  
Woven Composite ◽  
Ballistic Performance ◽  
Composite Systems ◽  
Matrix Cracks ◽  
Failure Evolution ◽  
Undesirable Property ◽  
Highly Porous

Abstract This investigation examines the role of porosity in the perforation resistance of 3-D woven fiber reinforced epoxy panels under impact by rigid projectiles at velocities of 100 to 200 m/s. Incident and residual velocities are measured to determine the energy absorption by the target. To compare samples of different areal density, the energy is normalized by the target areal density. The sample responses segregate by porosity, and the more highly porous samples absorb a greater amount of specific energy. The reason for this is unclear but may be due to the deflection of matrix cracks by pores or due to the greater flexibility of the fibers to absorb energy through tensile straining. Although porosity is generally an undesirable property in textile composites, the induction of porosity may result in reduced panel weight without degradation of ballistic performance, a clear advantage for weight minimization.

Detection and enumeration of microbial cells within highly porous calcareous reef sands

2006 ◽  
Vol 57 (4) ◽  
pp. 415 ◽  
Author(s):  
Christian Wild ◽  
Christian Laforsch ◽  
Markus Huettel
Keyword(s):  
Laser Scanning ◽  
Complex Surface ◽  
Porous Matrix ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Size Spectrum ◽  
Order Of Magnitude ◽  
Grain Surface ◽  
Highly Porous

In order to assess and to compare the abundances of prokaryotes in coral sands from three different areas in the Indo-Pacific, a technique was developed and evaluated for enumeration of prokaryotes living on and within calcareous grains. Propidium iodide labelling of prokaryotes and consecutive confocal laser scanning microscopy showed microbial colonisation within pores and small fissures of the coral sands. This embedded microbial colonisation required at least four extractions with weak acetic acid to dissolve the grain surface layer in order to detach 97% of the prokaryotic cells. Microbial enumeration based on this technique revealed that the abundance of prokaryotes in the carbonate sands were not significantly different among the three sites, but were about one order of magnitude higher than reported for silicate sands of a similar grain size spectrum. A possible reason for this high abundance of prokaryotes is the complex surface structure of the biogenic calcareous grains, their correspondingly highly porous matrix and the associated ability of prokaryotes to penetrate into carbonate grains. Our results highlight the role of calcareous reef sands as a substratum with a large specific surface area for prokaryotic colonisation and emphasise the contribution of calcium carbonate reef sands for element cycles in subtropical and tropical ecosystems.

Structural and thermal study of highly porous nanocomposite SiO2-based aerogels

2010 ◽  
Vol 356 (18-19) ◽  
pp. 879-883 ◽  
Author(s):  
Hexin Zhang ◽  
Yingjie Qiao ◽  
Xiaohong Zhang ◽  
Shuangquan Fang
Keyword(s):  
Thermal Study ◽  
Porous Nanocomposite ◽  
Highly Porous

scholarly journals The Role of Aluminium in the Synthesis of Mesoporous 4H Silicon Carbide

2015 ◽  
Vol 821-823 ◽  
pp. 970-973
Author(s):  
Jeanette Hvam ◽  
Per Morgen ◽  
Terence Edwin Warner ◽  
Eivind Morten Skou ◽  
Thomas Wolff
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Particulate Filter ◽  
High Porosity ◽  
Sintering Process ◽  
Diesel Particulate ◽  
High Temperature Reaction ◽  
Ternary Carbides ◽  
Highly Porous

Aluminium is found to play a key role in the process of forming a mechanically stable and highly porous and granular structure of 4H silicon carbide. The material is prepared by a high temperature reaction of the elemental constituents. The reactions are carried out under different background atmospheres, including nitrogen. Ternary carbides containing Al, Si and N, are formed in the process, and are believed to be responsible for the final outcome of the process, at the highest reaction temperatures, in the form of pure, well-connected grains of 4H-SiC forming a strong and rigid structure with high porosity. The Al containing compounds function as structural promoters for the 4H polytype recrystallization. This is expected - and partly shown - to take place through substitution with 4H-SiC and evaporation of all other constituents during the high temperature sintering step. When extruded into honeycomb structures prior to the sintering process this pure mesoporous SiC final product turns out to be ideal for a combined diesel particulate filter with support for catalysts in the pores.

Structural study of highly porous nanocomposite aerogels

2007 ◽  
Vol 353 (18-21) ◽  
pp. 1785-1788 ◽  
Author(s):  
Daniela Carta ◽  
Anna Corrias ◽  
Gavin Mountjoy ◽  
Gabriele Navarra
Keyword(s):  
Structural Study ◽  
Porous Nanocomposite ◽  
Highly Porous
Sign in / Sign up

Export Citation Format

Share Document