scholarly journals Bicomponent PLA Nanofiber Nonwovens as Highly Efficient Filtration Media for Particulate Pollutants and Pathogens

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 819
Author(s):  
Danyang Gao ◽  
Renhai Zhao ◽  
Xue Yang ◽  
Fuxing Chen ◽  
Xin Ning
Keyword(s):  
Lactic Acid ◽  
Pressure Drop ◽  
Polylactic Acid ◽  
Average Pore Size ◽  
Morphological Structure ◽  
Filtration Efficiency ◽  
High Porosity ◽  
Average Pore ◽  
Highly Efficient ◽  
Fibrous Membranes

Herein, a novel form of bicomponent nanofiber membrane containing stereo-complex polylactic acid (SC-PLA) was successfully produced by the side-by-side electrospinning of Poly (L-lactic acid) (PLLA) and Poly (D-lactic acid) (PDLA). We demonstrate that through these environmentally sustainable materials, highly efficient nanofiber assemblies for filtration can be constructed at very low basis weight. The physical and morphological structure, crystalline structure, hydrophobicity, porous structure, and filtration performance of the fibrous membranes were thoroughly characterized. It was shown that the fabricated polylactic acid (PLA) side-by-side fiber membrane had the advantages of excellent hydrophobicity, small average pore size, high porosity, high filtration efficiency, low pressure drop as well as superior air permeability. At the very low basis weight of 1.1 g/m2, the filtration efficiency and pressure drop of the prepared side-by-side membrane reached 96.2% and 30 Pa, respectively. Overall, this biomass-based, biodegradable filtration material has the potential to replace the fossil fuel-based polypropylene commercial meltblown materials for the design and development in filtration, separation, biomedical, personal protection and other fields.

scholarly journals Minimizing Drying Shrinkage and Enhancing Impermeability of Foam Concrete Modified with Epoxy Resin

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianqing Gong ◽  
Ke Li
Keyword(s):  
Surface Energy ◽  
Pore Size ◽  
Epoxy Resin ◽  
Average Pore Size ◽  
Drying Shrinkage ◽  
Maximum Level ◽  
High Porosity ◽  
Foam Concrete ◽  
Average Pore ◽  
Internal Pore Structure

Relatively high drying shrinkage and permeability were two of the major challenges associated with foam concrete (FC), primarily due to its high porosity nature. This study was aimed at reducing the drying shrinkage and improving the impermeability of FC by blending and modifying it with epoxy resin (EP). Extensive laboratory testing yielded an optimum content of 4.0% EP, corresponding to a minimum drying shrinkage rate of 1.47 mm/m, which was 48% lower than that of the unmodified FC. At this optimum dosage of 4.0% EP, the permeability pressure was at a maximum level of 1.4 MPa, whereas the permeability coefficient was at its lowest value of 0.75 × 10−9  mm/h. Internal pore structure and EP distribution were characterized using the scanning electron microscopy and indicated that a microgrid structure of the FC was formed internally, featuring an increase in the number of pores, a reduction in the average pore size, and a uniform pore size distribution. Similarly, surface energy measurements using the tensiometry method yielded maximum surface energy values at 4.0% EP content, which could be used to explain the reduced drying shrinkage and the enhanced impermeability characteristics of the modified FC.

scholarly journals Tailoring the strength and porosity of rapid-hardening magnesia phosphate paste via the pre-foaming method

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Li-Jie Liu ◽  
Jin-Hong Li ◽  
Xiang Wang ◽  
Ting-Ting Qian ◽  
Xiao-Hui Li
Keyword(s):  
Compressive Strength ◽  
Porous Structure ◽  
Bulk Density ◽  
Sodium Silicate ◽  
Average Pore Size ◽  
Hydration Product ◽  
Polypropylene Fibers ◽  
High Porosity ◽  
Average Pore ◽  
Maximum Compressive Strength

Abstract High-porosity magnesia phosphate paste (HPMPP) was prepared via the pre-foaming method. In the pre-foaming method, sintering treatment was not required. The bulk density and maximum compressive strength of the HPMPP prepared according to the ratio of water to solids (W/So) of 0.32 reached 464.00 ± 5.00 Kg/m3 and 0.30 ± 0.05 MPa, respectively. The compressive strength increased with the increases in the addition amounts of sodium silicate and polypropylene fibers. The bulk density of HPMPP increased with the increase in the addition of sodium silicate and decreased with the increase in the addition of polypropylene fibers. Besides, the porosity of the magnesia phosphate paste increased from 79.85% to 81.27% and from 80.31% to 83.75% after the addition of sodium silicate and polypropylene fibers respectively. The highest porosity (83.75%) of the prepared HPMPP was realized under the addition proportion (sodium silicate: polypropylene fibers: solids = 0.06:0.0025:1). The average pore size of the prepared HPMPP is about 180 μm and the pore distribution range is relatively narrow. The hydration product (struvite) is combined with MgO particle one by one and then coated on the surface of bubbles. With the decrease of the water content, after breaking bubbles, the porous structure can be achieved.

The Formation of Cobalt Chromium Molybdenum (CoCrMo) Foams Fabricated by Slurry Method

2016 ◽  
Vol 840 ◽  
pp. 197-201
Author(s):  
Sufizar Ahmad ◽  
M. Rosli ◽  
Nur Suliani Abdul Manaf ◽  
Murni Faridah Mahammad Rafter ◽  
Fazimah Mat Noor
Keyword(s):  
Sintering Temperature ◽  
Average Pore Size ◽  
Sem Analysis ◽  
High Porosity ◽  
Sintering Process ◽  
Cobalt Chromium ◽  
Average Pore ◽  
Slurry Method ◽  
Cobalt Chromium Molybdenum ◽  
Orthopedic Applications

Cobalt Chromium Molybdenum (CoCrMo) is a metal that are widely used in the biomedical field of orthopedic applications. CoCrMo foam was developed in the form of a porous structure where it has a high porosity on the surface with the different pore sizes and shapes. This research is intended to produce CoCrMo foam by using slurry method and to study the effect of composition and sintering temperature on the metal foams. The slurry of CoCrMo was prepared by mixing the binder materials of Methylcellulose (CMC), Polyethylene Glycol (PEG) and distilled water for an hour. Followed by mixing and stirring the CoCrMo powder for another 1 hour until it becomes slurries. Polyurethane (PU) foam was then impregnated into the slurry and dried for a day in the oven with 60 °C. Sintering process is carried out at temperature of 1000 °C, 1100 °C and 1200 °C using a tube furnace. Then sample of CoCrMo foam was going through a shrinkage measurement, microstructure analysis by using Scanning Electron Microscope (SEM), analysis of element by using Energy Diffraction X-ray (EDX) and also the density and porosity test by using Archimedes method. The sample with the composition of 65wt% was the best result in this experiment. While sintering temperature of 1200 °C produced the highest number of porosities. The shrinkage percentage is from 2.67% to 14.13%. The density obtained is in between 1.538 g/cm3 and 2.706 g/cm3 while the percentage of porosity is from 50.284% to 78.934%. The average pore size is in the range of 249.63μm to 445.38μm. The best sintering temperature and composition to produced high porosity were on 1200 °C and 65wt%.

Preparation SiC Ceramic Composite Filtration Membrane Materials by Dry Pressing and Synchronous Sintering Method

2013 ◽  
Vol 690-693 ◽  
pp. 409-414
Author(s):  
Kui Fan Su ◽  
Li Ming Wang ◽  
Xiang Yun Deng ◽  
Jian Bao Li ◽  
Chun Peng Wang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Particle Size ◽  
Pressure Drop ◽  
Pore Size ◽  
Ceramic Composite ◽  
Average Pore Size ◽  
Molding Pressure ◽  
Average Pore ◽  
Silicon Carbide Particle ◽  
Filtration Membrane

Silicon carbide ceramic composite filter membrane materials were prepared by dry pressure molding and synchronous sintering process at sintering temperature of 1300oC for 3h. and research the influence of on the molding pressure structure of SiC filtration membrane,effect of particle size on porosity, average pore size and filter pressure drop of filtration membrane, SEM was performed to examine the morphology, The porosity ,average pore size and filter pressure drop of filtration membrane were tested by Archimedes method ,bubble point method and filter pressure drop instrument. It is demonstrated that while the molding pressure (F) varied from 1MPa to 10MPa, the filter membrane material achieved preferable morphology and best performance when F equals to 5MPa. Under this modeling pressure, while silicon carbide particle size increased from 1 to 23μm, the pore ratio decreased from 48.0% to 36.2% and the average pore size increased from 0.35μm to 9.4μm, while the air gas velocity changed from 0 to 0.112m/s, the filter pressure drop increased, when the velocity is stable, the filter pressure drop reduced as the silicon carbide particle size.

scholarly journals Cytocompatibility of Bilayer Scaffolds Electrospun from Chitosan/Alginate-Chitin Nanowhiskers

Biomedicines ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 305
Author(s):  
Valentina A. Petrova ◽  
Alexey S. Golovkin ◽  
Alexander I. Mishanin ◽  
Dmitry P. Romanov ◽  
Daniil D. Chernyakov ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Electrostatic Interactions ◽  
Average Pore Size ◽  
Optimal Solution ◽  
Average Diameter ◽  
Solution Viscosity ◽  
High Porosity ◽  
Electrospinning Technique ◽  
Average Pore ◽  
Chitin Nanowhiskers

In this work, a bilayer chitosan/sodium alginate scaffold was prepared via a needleless electrospinning technique. The layer of sodium alginate was electrospun over the layer of chitosan. The introduction of partially deacetylated chitin nanowhiskers (CNW) stabilized the electrospinning and increased the spinnability of the sodium alginate solution. A CNW concentration of 7.5% provided optimal solution viscosity and structurization due to electrostatic interactions and the formation of a polyelectrolyte complex. This allowed electrospinning of defectless alginate nanofibers with an average diameter of 200–300 nm. The overall porosity of the bilayer scaffold was slightly lower than that of a chitosan monolayer, while the average pore size of up to 2 μm was larger for the bilayer scaffold. This high porosity promoted mesenchymal stem cell proliferation. The cells formed spherical colonies on the chitosan nanofibers, but formed flatter colonies and monolayers on alginate nanofibers. The fabricated chitosan/sodium alginate bilayer material was deemed promising for tissue engineering applications.

scholarly journals Factors Affecting Mass Transport Properties of Poly(ε-caprolactone) Membranes for Tissue Engineering Bioreactors

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 51 ◽  
Author(s):  
Nazely Diban ◽  
Beatriz Gómez-Ruiz ◽  
María Lázaro-Díez ◽  
Jose Ramos-Vivas ◽  
Inmaculada Ortiz ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Mass Transport ◽  
Pore Size ◽  
Transport Properties ◽  
Membrane Fouling ◽  
Average Pore Size ◽  
Lower Surface ◽  
High Porosity ◽  
Surface Porosity ◽  
Average Pore

High porosity and mass transport properties of microfiltration polymeric membranes benefit nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (approximately 0.7 µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case studies. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (approximately 0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more convenient to guarantee high flux of nutrients. On the contrary, having large external pore size (approximately 1.70 µm) and surface porosity would incur important internal protein fouling that could not be prevented with the operation mode and hydrodynamics of the perfusion system. Additionally, the use of glycerol in the drying protocols of the membranes might cause plasticization and a consequent reduction of mass transport properties due to membrane compaction by the pressure exerted to force perfusion. Therefore, preferentially, drying protocols that omit the use of plasticizing agents are recommended.

scholarly journals Effect of microsilica content on microstructure and properties of foamed ceramics with needle-like mullite

2019 ◽  
Vol 13 (2) ◽  
pp. 202-209 ◽  
Author(s):  
Wenying Zhou ◽  
Wen Yan ◽  
Nan Li ◽  
Yuanbing Li ◽  
Yajie Dai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Raw Materials ◽  
Average Pore Size ◽  
High Porosity ◽  
Sintering Process ◽  
Average Pore ◽  
Linear Change ◽  
Direct Foaming Method ◽  
Industrial Alumina

In this study, five foamed ceramics with struts containing needle-like mullite were prepared by direct-foaming method using white clay, industrial alumina and microsilica powder as raw materials. The effects of microsilica content on the phase compositions, microstructures and properties of foamed ceramics were investigated. The results showed that the adding of microsilica decreased the average pore size and apparent porosity and increased the compressive strength and thermal conductivity of the foamed ceramics by affecting the properties of foamed slurry and reaction sintering process. The foamed ceramics with 10 wt.% microsilica content showed the best properties with high porosity of 75.8%, positive reheating linear change, compressive strength of 1.44MPa and low thermal conductivity of 0.219W/(m?K) (at 350?C).

scholarly journals Factors Affecting Mass Transport Properties of Poly(Ε-Caprolactone) Membranes for Tissue Engineering Bioreactors

2018 ◽  
Author(s):  
Nazely Diban ◽  
Beatriz Gomez-Ruiz ◽  
Maria Lázaro-Díez ◽  
Jose Ramos-Vivas ◽  
Inmaculada Ortiz ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Mass Transport ◽  
Pore Size ◽  
Transport Properties ◽  
Membrane Fouling ◽  
Average Pore Size ◽  
Lower Surface ◽  
High Porosity ◽  
Surface Porosity ◽  
Average Pore

High porosity and mass transport properties of microfiltration polymeric membranes benefits nutrients supply to cells when used as scaffolds in interstitial perfusion bioreactors for tissue engineering. High nutrients transport is assumed when pore size and porosity of the membrane are in the micrometric range. The present work demonstrates that the study of membrane fouling by proteins present in the culture medium, though not done usually, should be included in the routine testing of new polymer membranes for this intended application. Two poly(ε-caprolactone) microfiltration membranes presenting similar average pore size (~0.7µm) and porosity (>80%) but different external surface porosity and pore size have been selected as case study. The present work demonstrates that a membrane with lower surface pore abundance and smaller external pore size (~0.67 µm), combined with adequate hydrodynamics and tangential flow filtration mode is usually more convenient to guarantee high flux of nutrients. On the contrary, having large external pore size (~1.70µm) and surface porosity would incur in important internal protein fouling that could not been prevented with the operation mode and hydrodynamics of the perfusion system. Additionally, the use of glycerol in the drying protocols of the membranes might cause plasticization and a consequent reduction of mass transport properties due to membrane compaction by the pressure exerted to force perfusion. Therefore, preferentially, drying protocols that omit the use of plasticizing agents are recommended.

Surface Modification and Properties of SiO2 Nano Porous Aerogels

2008 ◽  
Vol 373-374 ◽  
pp. 702-705 ◽  
Author(s):  
Xing Yuan Ni ◽  
Yang Li ◽  
Zhi Hua Zhang ◽  
Jun Shen ◽  
Bin Zhou ◽  
...  
Keyword(s):  
Surface Modification ◽  
Activated Carbon ◽  
Surface Property ◽  
Ambient Pressure ◽  
Average Pore Size ◽  
Activated Carbon Fiber ◽  
Toxic Substances ◽  
High Porosity ◽  
Average Pore ◽  
Oh Groups

Surface modification is a process in which Si-CH3 groups of trimethylchlorosilane (TMCS) replace -OH groups on the inner surface of SiO2 aerogels, so the surface property of aerogels has shown hydrophobic performance which could be changed back to hydrophilic by 450 heat treatment. This aerogels with surface property controlled are prepared via sol-gel process with polyethoxydisiloxanes (E-40) used as precursor, and have typical porous structures dried at ambient pressure: high porosity (above 90 %), super specific surface area (about 1000 m2/g), low bulk density (down to 3.03 kg/m3) and average pore size is about 20 nm. This paper presents adsorption mechanisms in aerogels and illustrates that the adsorption capacity of aerogels is three or four times as much as that of activated carbon fiber (ACF) and granule of activated carbon (GAC). So SiO2 aerogels are potentially important to be used as absorbents being quite efficient to adsorb toxic substances.

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