Factors Affecting the Pore Size in Porous Hydroxyapatite Produced by Stir-Froth-Polymerization Method

2007 ◽  
Vol 336-338 ◽  
pp. 1571-1573
Author(s):  
Jie Zhang ◽  
Xiao Shan Ning ◽  
Qun Fang Xiao ◽  
Lei Yang ◽  
Ke Xin Chen ◽  
...  
Keyword(s):  
Cell Size ◽  
Porous Ceramics ◽  
Ceramic Powders ◽  
Average Cell Size ◽  
Average Cell ◽  
Porous Hydroxyapatite ◽  
Factors Affecting ◽  
Polymerization Method ◽  
Highly Porous ◽  
Aqueous Slurry

Stir-froth-polymerization is a novel technique for producing highly porous ceramics, in which bubbles are formed by a mechanical frothing in aqueous slurry of ceramic powders. Many work had be done about the porosity, the permeability and the mechanical strength of the porous ceramics derived from this method, but there are still a lot of things remain unclear. This paper focuses on the mechanism of frothing, and the influence of parameters in the mechanical frothing. It was found that the stir time, the stir speed and the viscosity of the slurry have influence on the average cell-size and the distribution of them respectively. The average cell-size can be controlled in the range from 60 to 160 μm by adjusting the parameters.

Characterization of microstructures of SAN foam core using micro-computed tomography

2021 ◽  
pp. 026248932110068
Author(s):  
Youming Chen ◽  
Raj Das ◽  
Hui Wang ◽  
Mark Battley
Keyword(s):  
Cell Wall ◽  
Cell Size ◽  
Wall Thickness ◽  
Strain Localization ◽  
Cell Wall Thickness ◽  
Micro Computed Tomography ◽  
Average Cell Size ◽  
Average Cell ◽  
3D Images ◽  
Compressive Tests

In this study, the microstructure of a SAN foam was imaged using a micro-CT scanner. Through image processing and analysis, variations in density, cell wall thickness and cell size in the foam were quantitatively explored. It is found that cells in the foam are not elongated in the thickness (or rise) direction of foam sheets, but rather equiaxed. Cell walls in the foam are significantly straight. Density, cell size and cell wall thickness all vary along the thickness direction of foam sheets. The low density in the vicinity of one face of foam sheets leads to low compressive stiffness and strength, resulting in the strain localization observed in our previous compressive tests. For M80, large open cells on the top face of foam sheets are likely to buckle in compressive tests, therefore being another potential contributor to the strain localization as well. The average cell wall thickness measured from 2D slice images is around 1.4 times that measured from 3D images, and the average cell size measured from 2D slice images is about 13.8% smaller than that measured from 3D images. The dispersions of cell wall thickness measured from 2D slice images are 1.16–1.20 times those measured from 3D images. The dispersions of cell size measured from 2D slice images are 1.12–1.36 times those measured from 3D images.

The effect of organofluorine additives on the morphology, thermal conductivity and mechanical properties of rigid polyurethane and polyisocyanurate foams

2021 ◽  
pp. 0021955X2098715
Author(s):  
Cosimo Brondi ◽  
Ernesto Di Maio ◽  
Luigi Bertucelli ◽  
Vanni Parenti ◽  
Thomas Mosciatti
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Cell Size ◽  
Flexural Properties ◽  
Anisotropy Ratio ◽  
Cell Content ◽  
Average Cell Size ◽  
Average Cell ◽  
Thermal Insulating ◽  
Liquid Type

This study investigates the effect of liquid-type organofluorine additives (OFAs) on the morphology, thermal conductivity and mechanical properties of rigid polyurethane (PU) and polyisocyanurate (PIR) foams. Foams were characterized in terms of their morphology (density, average cell size, anisotropy ratio, open cell content), thermal conductivity and compressive as well as flexural properties. Based on the results, we observed that OFAs efficiently reduced the average cell size of both PU and PIR foams, leading to improved thermal insulating and mechanical properties.

Growth and Cell-Size Distribution of Marine Planktonic Algae in Batch and Dialysis Cultures

1973 ◽  
Vol 30 (2) ◽  
pp. 143-155 ◽  
Author(s):  
A. Prakash ◽  
Liv Skoglund ◽  
Britt Rystad ◽  
Arne Jensen
Keyword(s):  
Size Distribution ◽  
Cell Size ◽  
Growth Cycle ◽  
Exponential Growth Phase ◽  
Average Cell Size ◽  
Cell Size Distribution ◽  
Average Cell ◽  
Planktonic Algae ◽  
Maximum Cell ◽  
Dialysis Culture

An extended exponential growth phase and a higher maximum population characterized growth of planktonic algae in a dialysis system compared with that in a batch system. Algal cells grown in a dialysis culture had higher chlorophyll content and a larger average cell size than those grown in a batch culture. In both types of culture, changes in cell-size distribution were related to the phases of the growth cycle with maximum cell-size during the stationary phase. Various interactions of the component reactions of photosynthesis leading to changes in growth pattern and cell-size distribution are discussed.

Shear Induced Low- and High-Angle Boundary Characterization Using Kikuchi Bands in Transmission Electron Microscopy

2008 ◽  
Vol 584-586 ◽  
pp. 293-299 ◽  
Author(s):  
Marcello Cabibbo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Size ◽  
Grain Structure ◽  
Structure Evolution ◽  
High Angle ◽  
Boundary Misorientation ◽  
Average Cell Size ◽  
Average Cell ◽  
Transmission Electron

Microstructure evolution with equal channel angular pressing (ECAP) using route Bc, that is a 90° axial rotation of the billet between passes, up to 8 passes, was investigated by transmission electron microscopy. The study has been focused on the induced development of boundary misorientation and spacing toward microstructure refinement. Cell (low-angle) and grain (high-angle) misorientation and spacing were determined from about 250 boundaries per pass of ECAP, systematically using whether Kikuchi patterns or Moiré fringes, these latter where possible. The average cell size and misorientation saturate within the first two passes. Misorientation and spacing of high-angle boundaries decrease with the number of passes. After 8 passes, mean cell size is ≈ 1.3 µm and the fraction of high-angle boundaries is ≈ 0.7. Differences in rate of grain structure evolution per pass are linked to differences in ability of dislocations introduced in new passes to recombine with the existing ones. As ECAP strain rises, the misorientation distribution develops strong deviations from the MacKenzie distribution for statistical grain orientation. This is interpreted as a result of the tendency to form equiaxed grains in a textured grain structure.

Effect of Nanoclay on the Physical-Mechanical and Thermal Properties and Microstructure of Extruded Noncross-Linked LDPE Nanocomposite Foams

2011 ◽  
Vol 471-472 ◽  
pp. 751-756 ◽  
Author(s):  
F. Zandi ◽  
M. Rezaei ◽  
A. Kasiri
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Cell Size ◽  
Flame Retardancy ◽  
Image Analyzer ◽  
Mechanical And Thermal Properties ◽  
Average Cell Size ◽  
Cell Size Distribution ◽  
Average Cell ◽  
Nanocomposite Foams

Novel noncross-linked low density polyethylene (LDPE) foams were produced by extrusion process. In this study the effects of Organophilic Montmorillonite (OMMT) nanoclay (DK1) on thermal conductivity, flame retardancy, morphological and mechanical properties of LDPE foams have been investigated. Nanoclay dispersion in LDPE foam structure was examined by X-ray diffraction (XRD), microstructure was observed by an optical microscope and analyzed by Bel View image analyzer, thermal conductivity was studied by a simple transient method, mechanical properties was investigated using a tensile-compression Zwick-Roell machine as well as the flame retardancy of the samples was examined by flammability test. The optimum nanoclay content was determined by comparison of the properties in nanocomposite and neat LDPE foams. Due to the presence of nanoclay in the foam and decreasing the cell nucleation energy around the nanoclay, the average cell size was decreased as well as the cell density and microstructure uniformity was increased. In XRD patterns of LDPE nanocomposite foams, OMMT (DK1) characteristic peak was not observed as evidence of nanoclay intercalation-exfoliation in the polymer matrix, which led to the production of foams with homogenous microstructure. Furthermore, this nanocomposites showed lower thermal conductivity compared to neat LDPE foam, which can be attributed to the cell size reduction as well as narrow cell size distribution in nanocomposite foams. Compression test results demonstrated that LDPE nanocomposite foams with proper clay contents have improved mechanical properties (Young’s modulus, compressive strength). Furthermore due to the presence of DK1 nanoclay, LDPE foam showed a good char formation as an evidence of their flame retardancy.

Characterization of LDMMs

MRS Bulletin ◽  
1990 ◽  
Vol 15 (12) ◽  
pp. 41-43
Keyword(s):  
Spatial Scale ◽  
Cell Size ◽  
Three Dimensional ◽  
Morphological Properties ◽  
Sem Images ◽  
Average Cell Size ◽  
Cell Size Distribution ◽  
Average Cell ◽  
Process Step ◽  
Size Standard

The previous sections of this article described the synthesis, morphologies, and properties of a variety of low-density microcellular materials. This section discusses several of the analytical methods used and developed at the DOE laboratories to characterize these state-of-the-art materials.In some LDMM applications, quantitative measurements of the material's average cell size and cell size distribution are desired. Indeed, the term “microcellular” has little meaning without such information. As seen throughout this article, however, most LDMMs do not have a readily defined cellular character. The more general problem is to quantify the spatial scale(s) of the foam. For this purpose it is necessary to define one or more “measures” of the spatial scale. The possibilities are many and include not only single numbers (e.g., cell size and cell size standard deviation, where “cell size” is meaningful) but also functional descriptions (e.g., correlation functions).SEM provides direct images and, therefore, is the most popular technique for examining LDMM morphology. SEM, however, suffers from at least three limitations: (1) SEM examines only a very small volume of material, and thus is impractical for obtaining average morphological properties; (2) SEM requires that nonconductive LDMMs be coated, a process step that can alter the structure and introduce artifacts (particularly with delicate structures); and (3) SEM images are only two-dimensional projections of real three-dimensional structures.

Multiple effects of serum low-density lipoprotein on cultured human fibroblasts

1979 ◽  
Vol 57 (6) ◽  
pp. 684-691 ◽  
Author(s):  
M. J. Spain ◽  
L. O. Wosu ◽  
N. Kalant
Keyword(s):  
Cell Size ◽  
Human Fibroblasts ◽  
Density Lipoprotein ◽  
Cell Protein ◽  
Temporary Increase ◽  
Low Density ◽  
Cell Content ◽  
Average Cell Size ◽  
Platelet Factor ◽  
Average Cell

The effects of serum low-density lipoproteins (LDL) were studied in cultures of human skin fibroblasts grown in medium supplemented with human serum deficient in lipoproteins and in platelet factor. The LDL led to a temporary increase in the rate of cell replication, to increases in the cell content of protein and cholesterol, to an increase in average cell size, and to an increased secretion of glycosaminoglycans. The increases in cholesterol and protein were proportional to the increase in cell size, suggesting that the additional protein and cholesterol were of a structural, rather than a storage, nature. The increase in cell protein during the first few days of exposure to LDL was due to a decrease in the rate of protein degradation. Ultrafiltration of the serum to remove substances of molecular weight < 30 000 did not reduce the basal rate of cell proliferation but did prevent the stimulation of proliferation by LDL; it did not alter the effect of LDL on cell protein and cholesterol, indicating that the latter responses are independent of the mitogenic action. The response of cells from diabetic donors did not differ from that of normal cells.

DAPI direct counting underestimates bacterial abundances and average cell size compared to AO direct counting

1993 ◽  
Vol 38 (7) ◽  
pp. 1566-1570 ◽  
Author(s):  
Marcelino T. Suzuki ◽  
Evelyn B. Sherr ◽  
Barry F. Sherr
Keyword(s):  
Cell Size ◽  
Average Cell Size ◽  
Average Cell ◽  
Direct Counting

Effect of Foaming Temperature Control on Cell Size and Cell Density of Microcellular Plastics

2005 ◽  
Vol 24 (2) ◽  
pp. 91-102 ◽  
Author(s):  
Hidetaka Kawashima ◽  
Minoru Shimbo
Keyword(s):  
Cell Size ◽  
Cell Density ◽  
Average Cell Size ◽  
Average Cell ◽  
Blowing Agent ◽  
Microcellular Plastics ◽  
Temperature Method ◽  
Foamed Plastics ◽  
Maximum Cell ◽  
Foaming Temperature

In this study, noticing foaming temperature as a factor, which induces thermodynamic instability for cell nucleation of Microcellular plastics, the effect of control method of foaming temperature on cell size and cell density - that is number per unit volume of foamed plastics - were investigated. Generally, foaming by using batch process is carried out as follows. First, blowing agent is soaked into plastics until saturation under high pressure and soaking temperature. After plastics were saturated with blowing agent, pressure is released rapidly and then temperature is raised to foaming temperature and cells are nucleated and grown. Finally, rapid cooling controls cell growth. In this case, two methods can be considered for the control of foaming temperature. One is the elevated temperature method in which temperature is raised to foaming temperature and cells are grown after decompression in the foaming process. The other is the constant temperature method in which the temperature is already kept at foaming temperature before decompression. That is, it is the method of performing soaking and foaming at the same temperature. Polymethylmethacrylate (PMMA) resins were foamed under foaming conditions which the same foaming magnification is produced by both methods and cell size and cell density of foamed PMMA were investigated. As results, in case of production of the foamed plastics having the same foam magnification, it turned out that cell density of foamed plastics becomes large and average cell size becomes small but the maximum cell size becomes large by the elevated temperature method. On the other hand, although the maximum cell size becomes small, average cell size becomes large by the constant temperature method.

Study on Formula for Glass Fiber/Microcellular Unsaturated Polyester Composites Preparation

2011 ◽  
Vol 233-235 ◽  
pp. 2595-2599 ◽  
Author(s):  
Xue Ni Zhao ◽  
Bin Zhou ◽  
Wu Yong Wan ◽  
Shan Qi Zeng ◽  
Wei Ren
Keyword(s):  
Tensile Strength ◽  
Glass Fiber ◽  
Fiber Length ◽  
Unsaturated Polyester ◽  
Curing Agent ◽  
Average Cell Size ◽  
Average Cell ◽  
Factors Affecting ◽  
Styrene Content ◽  
Polyester Composites

Formula for glass fiber/microcellular unsaturated polyester composites (GF/MCUP) using supersaturated gas technology was studied by the way of orthogonal experiment. The results showed that these factors affecting average cell size from strongly to weakly were styrene content, accelerant content, glass fiber length, curing agent and glass fiber content, respectively. The factors affecting average cell density from strongly to weakly were accelerant content, styrene content, glass fiber content, curing agent content and glass fiber length, respectively. Curing agent content was the major factor affecting impact strength of GF/MCUP. The factors revealed no obvious difference in affecting tensile strength. Under the optimizing processing condition, the average cell size of GF/MCUP was about 8 μm and the cell density was 1.19×109 cells/cm3. The 153.70 and 255.84 % increase in impact strength were gained over that of GF/UP and UP, respectively. The corresponding 20.24 and 82.51% increase in tensile strength-to-weight ratio were gained over that of GF/UP and UP, respectively.

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