The Role of Solution and Coagulation Temperatures in Crystalline Structure, Morphology, Roughness, Pore Diameter Distribution, and Separation Properties of Nanoporous Membranes Fabricated Via Phase Inversion

2012 ◽  
Vol 47 (13) ◽  
pp. 1866-1873 ◽  
Author(s):  
A. Akbari ◽  
M. Hamadanian ◽  
M. Bojaran ◽  
A. Yunessnia Lehi ◽  
V. Jabbari
Keyword(s):  
Crystalline Structure ◽  
Phase Inversion ◽  
Pore Diameter ◽  
Diameter Distribution ◽  
Nanoporous Membranes ◽  
Structure Morphology

scholarly journals Mechanical and Microstructural Characteristics of Calcium Sulfoaluminate Cement Exposed to Early-Age Carbonation Curing

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3515
Author(s):  
Weikang Wang ◽  
Xuanchun Wei ◽  
Xinhua Cai ◽  
Hongyang Deng ◽  
Bokang Li
Keyword(s):  
Cement Paste ◽  
Pore Diameter ◽  
Performance Enhancement ◽  
Diameter Distribution ◽  
Early Age ◽  
Calcium Sulfoaluminate ◽  
Starting Point ◽  
And Performance ◽  
Curing Pressure ◽  
Carbonation Curing

: The early-age carbonation curing technique is an effective way to improve the performance of cement-based materials and reduce their carbon footprint. This work investigates the early mechanical properties and microstructure of calcium sulfoaluminate (CSA) cement specimens under early-age carbonation curing, considering five factors: briquetting pressure, water–binder (w/b) ratio, starting point of carbonation curing, carbonation curing time, and carbonation curing pressure. The carbonization process and performance enhancement mechanism of CSA cement are analyzed by mercury intrusion porosimetry (MIP), thermogravimetry and derivative thermogravimetry (TG-DTG) analysis, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that early-age carbonation curing can accelerate the hardening speed of CSA cement paste, reduce the cumulative porosity of the cement paste, refine the pore diameter distribution, and make the pore diameter distribution more uniform, thus greatly improving the early compressive strength of the paste. The most favorable w/b ratio for the carbonization reaction of CSA cement paste is between 0.15 and 0.2; the most suitable carbonation curing starting time point is 4 h after initial hydration; the carbonation curing pressure should be between 3 and 4 bar; and the most appropriate time for carbonation curing is between 6 and 12 h.

Hydrolysis of Zirconium Propoxide by an Esterification Reaction

1992 ◽  
Vol 271 ◽  
Author(s):  
I. Laaziz ◽  
A. Larbot ◽  
C. Guizard ◽  
A. Julbe ◽  
L. Cot
Keyword(s):  
Acetic Acid ◽  
Light Scattering ◽  
Crystalline Structure ◽  
Structure Determination ◽  
Nmr Spectra ◽  
Esterification Reaction ◽  
Zirconium Propoxide ◽  
Size Growth ◽  
Hydrolysis Of

ABSTRACTZirconium propoxide hydrolysis was performed with the help of an esterification reaction using acetic acid. Products, obtained according to the value of hydrolysis ratio, are successively crystals, sols and gels or precipitates. The similarity of FUR and NMR spectra for crystals and gels allows to think that the arrangements of ligands around the zirconium atoms are close. The crystalline structure determination permits to precise the environment : acetate groups are always bridging and propoxy groups can be bridging or terminal. Clusters containing 9 zirconium atoms, bridged by oxygen atoms, exist in the structure. The colloid size growth was performed by light scattering. A discussion of the role of acetic acid and the competition between the possible reactions is given.

Research on Influence of Wetting Fluid by Gas Bubble Method to Measure Pore Size Characteristics

2014 ◽  
Vol 1048 ◽  
pp. 498-502
Author(s):  
Peng Zhang ◽  
Bing Xuan Ni
Keyword(s):  
Normal Distribution ◽  
Pore Diameter ◽  
Diameter Distribution ◽  
Gas Bubble ◽  
Distribution Characteristics ◽  
Measurement Results ◽  
Dimethyl Silicone ◽  
Composite Nonwoven ◽  
Liquid Measurement ◽  
Wetting Liquid

In this paper, the experimental of pore diameter distribution characteristics of spunbond and meltblown composite nonwoven is carried out by using of gas bubble method. The influence of 7 kinds of wetting liquid to measurement results is studied, including of Galwick, Porefil, Silpore, Silwick, Dimethyl silicone, Isopropanol and Alcohol. The results show that wetting liquids of Galwick, Silwick and Dimethyl silicone can obtain the consistent value of pore diameter, meanwhile, have nearly normal distribution characteristics of pore diameter. Therefore, the wetting liquids of Galwick, Silwick and Dimethyl silicone are ideal wetting liquid for nonwoven. While the other four kinds of wetting liquid measurement results vary greatly, and don’t show normal distribution, they are not suitable as the wetting liquid of nonwoven by gas bubble method.

In-Plane Microstructure of Gas Diffusion Layers With Different Properties for PEFC

2013 ◽  
Author(s):  
Mehdi Mortazavi ◽  
Kazuya Tajiri
Keyword(s):  
Contact Angle ◽  
Fuel Cell ◽  
Pore Diameter ◽  
Gas Transport ◽  
Gas Permeability ◽  
Transport Phenomena ◽  
Gas Diffusion ◽  
Polymer Electrolyte Fuel Cell ◽  
Diameter Distribution ◽  
Carbon Paper

Gas diffusion layer (GDL) is undoubtedly one of the most complicated components used in a polymer electrolyte fuel cell (PEFC) in terms of liquid and gas transport phenomena. An appropriate fuel cell design seeks a fundamental study of this tortuous porous component. Currently, porosity and gas permeability have been known as some of the key parameters affecting liquid and gas transport through GDL. Although these are dominant parameters defining mass transport through porous layers, there are still many other factors affecting transport phenomena as well as overall cell performance. In this work, microstructural properties of Toray carbon papers with different thicknesses and for polytetrafluoroethylene (PTFE) treated and untreated cases have been studied based on scanning electron microscopy (SEM) image analysis. Water droplet contact angle as a dominant macroscale property as well as mean pore diameter, pore diameter distribution, and pore roundness distribution as important microscale properties have been studied. It was observed that the mean pore diameter of Toray carbon paper does not change with its thickness and PTFE content. Mean pore diameter for Toray carbon papers was calculated to be around 26μm regardless of their thicknesses and PTFE content. It was also observed that droplet contact angle on GDL surface does not vary with GDL thickness. The average contact angle for 10 wt.% PTFE treated GDLs of different thicknesses was measured about 150°. Finally, the heterogeneous in-plane PTFE distribution on the GDL surface was observed to have no effect on mean pore diameter of GDLs.

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