Preparation of macroporous biodegradable poly(L-lactide-co-ϵ-caprolactone) foams and characterization by mercury intrusion porosimetry, image analysis, and impedance spectroscopy

2003 ◽  
Vol 66A (2) ◽  
pp. 199-213 ◽  
Author(s):  
V. Maquet ◽  
S. Blacher ◽  
R. Pirard ◽  
J.-P. Pirard ◽  
M. N. Vyakarnam ◽  
...  
1991 ◽  
Vol 245 ◽  
Author(s):  
H. Igarashi ◽  
T. Takahashi

ABSTRACTMDF(Macro-Defect-Free ) cement pastes, which consist of portland cement and polyvinyl alcohol/acetate, were prepared by varying the temperature during pressing and drying operations. We then examined the expansion of MDF cement pastes at various constant humidities. There was a large difference in expansion above 60%R.H. between samples prepared varying temperature at which samples were pressed. Samples pressed at 90 °C showed less expansion than samples pressed at 40 °C.The pore structure of MDF cement pastes before exposure to moisture was measured by nitrogen adsorption, mercury intrusion porosimetry and image analysis. The properties of a matrix containing polyvinyl alcohol/acetate and cemnt hydrates were also investigated by TEM, IR and XPS.There were not large differences in the result of IR and XPS measurement between the MDF cement pastes prepared at various temperatures. Calcium hydroxide crystal, lying perpendicular to cement particles, were often observed only in the MDF cement pastes pressed at 90 °C which occurs by water absorption, seems to be suppressed by calcium hydroxide crystal.


Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1823
Author(s):  
Won-Kyung Kim ◽  
Young-Ho Kim ◽  
Gigwon Hong ◽  
Jong-Min Kim ◽  
Jung-Geun Han ◽  
...  

This study analyzed the effects of applying highly concentrated hydrogen nanobubble water (HNBW) on the workability, durability, watertightness, and microstructure of cement mixtures. The number of hydrogen nanobubbles was concentrated twofold to a more stable state using osmosis. The compressive strength of the cement mortar for each curing day was improved by about 3.7–15.79%, compared to the specimen that used general water, when two concentrations of HNBW were used as the mixing water. The results of mercury intrusion porosimetry and a scanning electron microscope analysis of the cement paste showed that the pore volume of the specimen decreased by about 4.38–10.26%, thereby improving the watertightness when high-concentration HNBW was used. The improvement in strength and watertightness is a result of the reduction of the microbubbles’ particle size, and the increase in the zeta potential and surface tension, which activated the hydration reaction of the cement and accelerated the pozzolanic reaction.


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