scholarly journals Preparation and characterization of PTFE flat sheet membrane: Effect of sodium benzoate content

2017 ◽  
Vol 13 (4) ◽  
pp. 598-601
Author(s):  
Faezeah Abd Ghani ◽  
Khaidir Hamzah ◽  
Wan Norharyati Wan Salleh ◽  
Hasimah Mohamed
Keyword(s):  
Surface Roughness ◽  
Pore Size ◽  
Sodium Benzoate ◽  
Sem Analysis ◽  
Average Pore ◽  
Force Microscopy ◽  
Flat Sheet ◽  
Pore Size Distributions ◽  
Flat Sheet Membrane ◽  
Porous Microstructures

Polytetrafluoroethylene (PTFE) flat sheet membranes were prepared through casting and sintering methods. The effect of sodium benzoate salt on the characteristics of PTFE flat sheet membranes such as  morphology, surface roughness, porosity, mechanical strength and crystallinity were studied through scanning electron microscopy (SEM), atomic force microscopy (AFM), mercury intrusion porosimetry, tensile test and X-ray diffraction (XRD). SEM analysis confirmed the formation of irregular porous microstructures in sponge-like configuration. All the fabricated membranes exhibited narrow pore size distributions and have relatively small average pore diameters between 0.074 and 1.068 µm despite having porosity between 36.41 and 74.32 %. In addition, the roughness of the PTFE flat sheet membranes increased as the sodium benzoate content increased. Increasing sodium benzoate content was positive for pore size, porosity and roughness but negative for surface roughness and mechanical properties. This research confirmed that the addition of sodium benzoate salt in aqueous PTFE solution is a useful approach for the fabrication of porous PTFE flat sheet membranes

Determination of Pore Size Distributions in Nano-Porous Thin Films from Small Angle Scattering

2003 ◽  
Vol 766 ◽  
Author(s):  
Barry J. Bauer ◽  
Ronald C. Hedden ◽  
Hae-Jeong Lee ◽  
Christopher L. Soles ◽  
Da-Wei Liu
Keyword(s):  
Pore Size ◽  
Small Angle ◽  
Length Distribution ◽  
Dielectric Constants ◽  
Scattering Data ◽  
Size Distributions ◽  
Average Pore ◽  
Pore Size Distributions ◽  
Phase Size

AbstractSmall angle neutron and x-ray scattering (SANS, SAXS) are powerful tools in determination of the pore size and content of nano-porous materials with low dielectric constants (low-k) that are being developed as interlevel dielectrics. Several models have been previously applied to fit the scattering data in order to extract information on the average pore and/or matrix size. A new method has been developed to provide information on the size distributions of the pore and matrix phases based on the “chord length distribution” introduced by Tchoubar and Mering. Examples are given of scattering from samples that have size distributions that are narrower and broader than the random distribution typical of scattering described by Debye, Anderson, and Brumberger. An example of fitting SANS data to a phase size distribution is given.

Effect of Heat-Treatment in Ar Atmosphere on Pore Structure of Carbonaceous Materials from Polysiloxane

2014 ◽  
Vol 602-603 ◽  
pp. 279-284
Author(s):  
Li Qun Duan ◽  
Chen Chen Zhang ◽  
Qing Song Ma ◽  
Zhao Hui Chen
Keyword(s):  
Heat Treatment ◽  
Pore Structure ◽  
Pore Size ◽  
Pore Volume ◽  
Average Pore Size ◽  
Total Pore Volume ◽  
Treatment Temperature ◽  
Carbonaceous Materials ◽  
Average Pore ◽  
Pore Size Distributions

Nanoporous carbonaceous materials derived from polysiloxane were first prepared by pyrolysis at 1300°C followed with hydrofluoric acid (HF) etching treatment. Their thermal stability of pore structure in inert condition was investigated in this paper by nitrogen adsorption technique in detail. The specific surface area (SSA) and pore volume (total pore volume, micropore volume, mesopore volume) decreased continually in the heat-treatment temperature range of 1000~1400°C. The average pore size almost kept the same with the raw sample. However, when the temperature exceeded 1400°C, the micropore interconnection began transforming to mesopore structure, which led to the decline of SSA and the increase of average pore size. Furthermore, the pore size distributions (PSDs) curves showed that heat-treatment had an advantage on the transition process of pore structure from disorder to regularity to some extent when heat-treated in the range 1000~1400°C for the most possible reason of relief of residue strain in the carbonaceous materials.

Ni and Cu Incorporated Mesoporous Nanocomposite Catalytic Materials

2008 ◽  
Vol 8 (2) ◽  
pp. 549-556 ◽  
Author(s):  
Asli Nalbant ◽  
Timur Dogu ◽  
Suna Balci
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Atomic Ratio ◽  
Nanocomposite Materials ◽  
Size Distributions ◽  
Hydrothermal Route ◽  
Average Pore ◽  
Pore Size Distributions ◽  
Xrd Patterns ◽  
Mcm 41

Nickel and copper incorporated MCM-41-like mesoporous nanocomposite materials prepared by the direct hydrothermal synthesis and the impregnation procedures showed highly attractive pore structure and surface area results for catalytic applications. The XRD patterns showed that characteristic MCM-41 structure was preserved for the materials synthesized following an impregnation procedure before the calcination step. The surface area of the Cu impregnated material with a quite high Cu/Si atomic ratio (0.19) was 631 m2/g. Very narrow pore size distributions with an average pore diameter of about 2.7 nm were obtained as a result of plugging of some of the smaller pores by Cu nanoballs. For lower metal to Si ratios (for instance for Ni/Si = 0.06) much higher surface area values (1130 m2/g) were obtained. In the case of nanocomposite materials synthesized by the direct hydrothermal route, MCM-41 structure was not destroyed for samples containing metal to Si atomic ratios as high as 0.12. In the case of materials containing Cu/Si and Ni/Si ratios over 0.2 wider pore size distributions and some decrease of surface area were observed.

scholarly journals Surface Topography, Gloss and Flexural Strength of Pressable Ceramic After Finishing-Polishing Protocols

2019 ◽  
Vol 30 (2) ◽  
pp. 164-170 ◽  
Author(s):  
Fernanda P. Silva ◽  
Ana L. R. Vilela ◽  
Matheus M. G. Almeida ◽  
André R. F. Oliveira ◽  
Luís H. A. Raposo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Flexural Strength ◽  
Glass Ceramic ◽  
Lower Surface ◽  
Good Alternative ◽  
Sem Analysis ◽  
Force Microscopy ◽  
Biaxial Flexural Strength ◽  
Surface Irregularities ◽  
Post Hoc

Abstract This study evaluated the effect of different finishing-polishing protocols on surface roughness, gloss, morphology and biaxial flexural strength of pressable fluorapatite glass ceramic. Thirty ceramic discs (12x1 mm) were produced and divided into five groups (n=6): CT: control (glaze); DA: fine grit diamond bur; DG: DA + new glaze layer; DP: DA + felt disk with fine grit diamond paste; DK: DA+ sequential polishing with silicon abrasive instruments, goat hair brush and cotton wheel. The specimens were analyzed for surface roughness (Ra) under profilometry and atomic force microscopy (AFM). Gloss was measured with spectrophotometry and micromorphology with scanning electron microscopy (SEM). Flexural strength was assessed by biaxial flexural strength test. Data were analyzed using one-way ANOVA and Tukey’s post hoc test (a=0.05). DK showed the lowest surface roughness values and DA presented the highest in the perfilometer analysis. No significant differences were observed in the AFM for the CT, DG and DK groups, which presented the lower surface roughness; DA and DP had the higher Ra values. The DA, DP and CT showed the lowest surface gloss values, and the reflectance was significantly different from those observed for DK and DG groups. SEM analysis revealed the smoothest surface for DK group, followed by DG and CT groups; DA and DP groups exhibited variable degrees of surface irregularities. No significant differences were observed among groups for the biaxial flexural strength. The polishing protocol used in DK group can be a good alternative for chairside finishing of adjusted pressable fluorapatite glass ceramic surfaces.

Evaluation of the Effect of Catalyst Pore-Size Distribution on the Effectiveness Factor in Ethylbenzene Dehydrogenation by Orthogonal Collocation

2011 ◽  
Vol 316-317 ◽  
pp. 155-169
Author(s):  
Mohammad Ebrahim Zeynali
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Effectiveness Factor ◽  
Orthogonal Collocation ◽  
Average Pore ◽  
Catalyst Pellet ◽  
Pore Size Distributions ◽  
Styrene Production

The mathematical model for multicomponent diffusion in styrene production is given considering all six reactions involved in styrene production. The diffusion coefficients for catalyst pellet are calculated for unimodal and bimodal pore size distributions using trapezoidal rule of integration. The effects of standard deviation and average pore size on the diffusion coefficient are determined. The differential equations are converted to algebraic equations and solved by the orthogonal collocation method. The effectiveness factor of catalyst pellet in styrene production is calculated for various pore sizes. It is seen that the average pore size and pore size distribution affects the production rate and effectiveness factor significantly.

AFM study of the dynamics of α-alumina surface faceting during high-temperature processing

1995 ◽  
Vol 53 ◽  
pp. 334-335 ◽  
Author(s):  
Michael W. Bench ◽  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
High Temperature ◽  
Thin Foil ◽  
Sem Analysis ◽  
Conductive Coatings ◽  
Force Microscopy ◽  
Minimal Sample ◽  
Atomic Force ◽  
Formation And Evolution ◽  
High Temperature Processing ◽  
Nominal Surface

To gain a better understanding of the surface faceting that occurs in α-alumina during high temperature processing, atomic force microscopy (AFM) studies have been performed to follow the formation and evolution of the facets. AFM was chosen because it allows for analysis of topographical details down to the atomic level with minimal sample preparation. This is in contrast to SEM analysis, which typically requires the application of conductive coatings that can alter the surface between subsequent heat treatments. Similar experiments have been performed in the TEM; however, due to thin foil and hole edge effects the results may not be representative of the behavior of bulk surfaces.The AFM studies were performed on a Digital Instruments Nanoscope III using microfabricated Si3N4 cantilevers. All images were recorded in air with a nominal applied force of 10-15 nN. The alumina samples were prepared from pre-polished single crystals with (0001), , and nominal surface orientations.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Brittle Behaviour in Aspirin Crystals: Evidence of Spalling Fracture

2020 ◽  
Author(s):  
Benjamin P. A. Gabriele ◽  
Craig J. Williams ◽  
Douglas Stauffer ◽  
Brian Derby ◽  
Aurora J. Cruz-Cabeza
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Single Crystals ◽  
Spalling Fracture ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging

<div> <div> <div> <p>Single crystals of aspirin form I were cleaved and indented on their dominant face. Upon inspection, it was possible to observe strongly anisotropic shallow lateral cracks due to the extreme low surface roughness after cleavage. Atomic Force Microscopy (AFM) imaging showed spalling fractures nucleating from the indent corners, forming terraces with a height of one or two interplanar spacings d100. The formation of such spalling fractures in aspirin was rationalised using basic calculations of attachment energies, showing how (100) layers are poorly bonded when compared to their relatively higher intralayer bonding. An attempt at explaining the preferential propagation of these fractures along the [010] direction is discussed. </p> </div> </div> </div>

Brittle Behaviour in Aspirin Crystals: Evidence of Spalling Fracture

2020 ◽  
Author(s):  
Benjamin P. A. Gabriele ◽  
Craig J. Williams ◽  
Douglas Stauffer ◽  
Brian Derby ◽  
Aurora J. Cruz-Cabeza
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Single Crystals ◽  
Spalling Fracture ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging

<div> <div> <div> <p>Single crystals of aspirin form I were cleaved and indented on their dominant face. Upon inspection, it was possible to observe strongly anisotropic shallow lateral cracks due to the extreme low surface roughness after cleavage. Atomic Force Microscopy (AFM) imaging showed spalling fractures nucleating from the indent corners, forming terraces with a height of one or two interplanar spacings d100. The formation of such spalling fractures in aspirin was rationalised using basic calculations of attachment energies, showing how (100) layers are poorly bonded when compared to their relatively higher intralayer bonding. An attempt at explaining the preferential propagation of these fractures along the [010] direction is discussed. </p> </div> </div> </div>

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