scholarly journals ELECTROSPINNING OF ANTIBACTERIAL POLYURETHANE/ZnO NANOFIBERS

2021 ◽  
Vol 2021 ◽  
pp. 185-192
Author(s):  
İ.Y. Mol ◽  
F.C. Çallioğlu
Keyword(s):  
Surface Tension ◽  
Antibacterial Activity ◽  
Water Vapour ◽  
Fibre Diameter ◽  
Water Vapour Permeability ◽  
Solution Viscosity ◽  
Optimum Process ◽  
Solution Properties ◽  
Vapour Permeability ◽  
Zno Nanofibers

In this study, it is aimed to produce and characterize antibacterial polyurethane (PU)/Zinc oxide (ZnO) nanofibers by electrospinning method. Firstly, polymer solutions were prepared at various ZnO concentrations such as 0, 0.2, 0.4, 0.6, 0.8, 1. Then solution properties (conductivity, viscosity, surface tension) were determined and analysed the effects of ZnO concentration on the solution properties. PU/ZnO nanofibers produced via electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate and atmospheric conditions). Finally, the nanofibers were characterized in terms of fibre morphology, thermal stability, permeability and antibacterial activity using SEM-EDS, DSC-TGA, water vapour permeability and disk diffusion methods. According to the solution results; it was observed that conductivity and surface tension decrease significantly with ZnO addition. On the other hand, solution viscosity increases as the ZnO concentration increases. From the SEM images, it has been seen clearly that average fibre diameter increases with ZnO concentration and incorporation of ZnO particles to the fibre structure was verified by SEM-EDS. According to the thermal analyse result, nanofibers begin to degrade between 271.94 ºC and 298.73 ºC. In addition, water vapour permeability increases as the ZnO concentration increase. Lastly antibacterial activity against gram negative (E.coli) and gram positive (S. aureus) was determined with specific zone diameter.

scholarly journals Comparative analysis of superabsorbent properties of PVP and PAA nanofibres

2021 ◽  
Vol 72 (04) ◽  
pp. 460-466
Author(s):  
BUKET GÜLER ◽  
FUNDA CENGİZ ÇALLIOĞLU
Keyword(s):  
Surface Tension ◽  
Comparative Analysis ◽  
Fibre Diameter ◽  
Volume Ratio ◽  
High Specific Surface Area ◽  
Absorption Capacity ◽  
Solution Viscosity ◽  
Optimum Process ◽  
Absorption Properties ◽  
Synthetic Urine

This study presents the comparative analysis of production, characterization and absorption properties of Polyvinylpyrrolidone (PVP) and Polyacrylic acid (PAA) nanofibres. Firstly, optimization studies about polymer (PVP and PAA), superabsorbent additive (waterlock)(WL) and crosslinker agent (sodium persulfate and glutaraldehyde)concentrations were achieved. Then solution properties such as conductivity, surface tension and viscosity were determined. Electrospinning was carried out under the optimum process parameters (voltage, distance between the electrodes, solution feed rate etc.) to obtain superabsorbent nanofibrous surfaces. Surface and fibre morphologies were analysed with Scanning Electron Microscopy (SEM) and thickness of nanoweb and weight in grams of nanofibres were also measured. Lastly, optimized PVP and PAA nanofibres were compared in terms of absorption properties with water and synthetic urine with various times from 5 to 86400 seconds. According to the results, generally fine, smooth and uniform nanofibres were obtained. It was observed that the solution viscosity, conductivity, and average fibre diameter increase with waterlock (WL) and cross-linker additions while surface tension was not change. In addition, PAA nanofibres’ absorption capacity with water and synthetic urine was higher than PVP nanofibres, while PVP nanofibres’ absorption rate is higher. It is possible to say that electrospun nanofibrous surfaces that are ultra-thin, light, porous and with high specific surface area to volume ratio are promising for new superabsorbent materials.

scholarly journals SOLVENT OPTIMIZATION OF ELECTROSPUN POLY(ACRYLIC ACID) NANOFIBERS

2021 ◽  
Vol 2021 ◽  
pp. 178-184
Author(s):  
M. Geysoğlu ◽  
F.C. Çallıoğlu
Keyword(s):  
Surface Tension ◽  
Acrylic Acid ◽  
Ph Value ◽  
Fibre Diameter ◽  
Optimum Process ◽  
Distilled Water ◽  
Solution Properties ◽  
Atmospheric Conditions ◽  
Fibre Morphology ◽  
Poly Acrylic Acid

In this study, it was investigated experimentally the influence of various solvents (distilled water and ethanol) on the solution properties, spinning performance, and fibre morphology of the electro spun Poly (acrylic acid) nanofibers. Firstly, polymer solutions were prepared at 5 wt % PAA with various solvent ratios of ethanol and distilled water. Then, solution properties such as viscosity, density, pH, conductivity, and surface tension were determined. The production of nanofiber samples was carried out by electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate, and atmospheric conditions). Finally, the morphological characterization of the nanofiber surface was carried out with SEM. According to the results, it was observed that conductivity, surface tension and the density of the solution increase as the ethanol ratio decreases. On the other hand, pH value increases as the ethanol ratio increases and, so, the acidic value of the solutions decreases. The viscosity increased until the ethanol/distilled water ratio was 50/50 and then decreased as the ethanol percentage decreased to under 50%. In addition, average fibre diameter decreases with ethanol ratio decreases. It is possible to say that solvent type affects solution properties, fibre morphology and spinning performance significantly. Generally, fine, uniform and bead free nanofibers could be electro spun and the PAA solution containing 70 wt % distilled water and 30 wt % ethanol was selected as the optimum in terms of fibre morphology, web quality and spinning performance.

Using Control Chart to Detect Abnormal Changes in the Permeability

2013 ◽  
Vol 779-780 ◽  
pp. 319-322
Author(s):  
Ming Hung Shu ◽  
Jui Chan Huang ◽  
Thanh Lam Nguyen ◽  
Bi Min Hsu
Keyword(s):  
Water Vapour ◽  
Average Run Length ◽  
Stable Process ◽  
Critical Factor ◽  
Water Vapour Permeability ◽  
Control Signal ◽  
Process Mean ◽  
Vapour Permeability ◽  
Practical Applications ◽  
Printing Papers

Water-vapour permeability is a critical factor of writing/ printing papers in most of practical applications; but how to monitor the manufacturing process to keep the key characteristic of the paper in control is still understudied. Therefore, in this paper, in order to monitor the water-vapour permeability of writing/ printing papers, MaxGWMA chart is first suggested due to its best effectiveness in terms of average run length performance and its high capability of detecting small shifts in the process mean and variability as well as identifying the source and the direction of an out-of-control signal. By using MaxGWMA chart, assignable causes of any out-of-control signal should be deeply examined so as to have proper corrective actions undertaken to either eliminate them from the process or reduce the variability induced by them to make the papers consistently manufactured under a stable process.

scholarly journals Hygrothermal simulation of building performance: data for Scottish masonry materials

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
P. F. G. Banfill
Keyword(s):  
Thermal Conductivity ◽  
Water Vapour ◽  
Material Properties ◽  
Simulation Software ◽  
Water Vapour Permeability ◽  
High Porosity ◽  
Water Absorption Coefficient ◽  
Vapour Permeability ◽  
Hygrothermal Simulation ◽  
Current Production

AbstractRetrofitting thermal insulation to solid masonry walls alters their hygrothermal behaviour, which can be modelled by hygrothermal simulation software. However, such software needs values of key material properties to ensure satisfactory results and until now data has not been available for Scottish masonry buildings. This work aims to contribute to a Scotland-specific dataset of material properties for use by designers working on such buildings. Thermal conductivity, water vapour permeability, sorptivity, water absorption coefficient, hygroscopic sorption, density and porosity were all determined experimentally for selected historic and contemporary masonry materials. Within the range of materials tested three groups of materials properties emerge. Natural hydraulic lime mortars, hot-mixed quicklime mortar and earth mortar all show comparatively low density, high porosity, low thermal conductivity, high water vapour permeability and variable but generally high hygroscopic sorption. Craigleith, Hailes and Giffnock sandstones, no longer available but obtained from conservation works on historic buildings, and Locharbriggs and Hazeldean sandstones, obtained from current production, all show intermediate values of these properties. Crathes granodiorite and Scottish whinstone (from current production) show high density, low porosity, high thermal conductivity, low water vapour permeability and low hygroscopic sorption. It is shown that these materials are all relevant to Scottish buildings constructed in traditional masonry and this paper presents the first comprehensive set of hygrothermal property data for them.

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