Formation of unilamellar vesicles by repetitive freeze-thaw cycles: characterization by electron microscopy and 31 P-nuclear magnetic resonance

2000 ◽  
Vol 29 (3) ◽  
pp. 184-195 ◽  
Author(s):  
Mounir Traïkia ◽  
Dror E. Warschawski ◽  
Michel Recouvreur ◽  
Jean Cartaud ◽  
Philippe F. Devaux
Keyword(s):  
Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Unilamellar Vesicles ◽  
Freeze Thaw ◽  
Nuclear Magnetic

scholarly journals C-S-H Pore Size Characterization Via a Combined Nuclear Magnetic Resonance (NMR)–Scanning Electron Microscopy (SEM) Surface Relaxivity Calibration

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1779 ◽  
Author(s):  
Christoph Naber ◽  
Florian Kleiner ◽  
Franz Becker ◽  
Long Nguyen-Tuan ◽  
Christiane Rößler ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ion Beam ◽  
New Method ◽  
Sem Images ◽  
Surface Relaxivity ◽  
Scanning Electron ◽  
Nuclear Magnetic

A new method for the nuclear magnetic resonance (NMR) surface relaxivity calibration in hydrated cement samples is proposed. This method relies on a combined analysis of 28-d hydrated tricalcium silicate samples by scanning electron microscopy (SEM) image analysis and 1H-time-domain (TD)-NMR relaxometry. Pore surface and volume data for interhydrate pores are obtained from high resolution SEM images on surfaces obtained by argon broad ion beam sectioning. These data are combined with T2 relaxation times from 1H-TD-NMR to calculate the systems surface relaxivity according to the fast exchange model of relaxation. This new method is compared to an alternative method that employs sequential drying to calibrate the systems surface relaxivity.

scholarly journals Microscopic Characteristic Analysis on Sandstone under Coupling Effect of Freeze–Thaw and Acidic Treatment: From Nuclear Magnetic Resonance Perspective

2020 ◽  
Vol 10 (16) ◽  
pp. 5699
Author(s):  
Songtao Yu ◽  
Hongwei Deng ◽  
Guanglin Tian ◽  
Junren Deng
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Acid Solution ◽  
Coupling Effect ◽  
Fractal Dimensions ◽  
Total Porosity ◽  
Characteristic Analysis ◽  
Freeze Thaw ◽  
Ph Decrease ◽  
Nuclear Magnetic

Microscopic characteristics greatly affect mechanical and physical properties as they exert vital impact on the stability and durability of materials. In this paper, widely distributed sandstone was chosen as the research object. Sandstone was treated with a coupled effect of Freeze–Thaw (F–T) weathering and acid solution, where freeze–thaw cycles were set as 0, 10, 20, 30 and 40 cycles, and the pH of the acid solution were set as 2.8, 4.2, 5.6 and 7.0, respectively. Then, nuclear magnetic resonance was applied to measure the microscopic characteristics of sandstone, then porosity, pore size distribution and permeability before the fractal dimensions were obtained and calculated. Results show that porosity increases when F–T cycles increase, and its increase grows with the pH of acid solution decrease during the first 10 F–T cycles. Macro porosity, meso porosity and micro porosity account for the largest, second largest and smallest ratio of porosity growth. Meso porosity, micro porosity and macro porosity account for the largest, second largest and smallest ratio of total porosity. Permeability increases obviously with F–T cycle increase, while acid erosion exerts little influence on permeability increment overall. Fractal dimensions of meso pores and macro pores increase with F–T cycle increase overall, and they increase with pH decrease overall. Porosity has strong exponentially correlation with permeability. Fractal dimensions of meso pores and macro pores have good linearly correlation with permeability, while correlation between porosity and fractal dimensions are not that obvious.

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