scholarly journals Self-Regulating Electrically Conductive Materials Based on Polyethylene Compositions with UHMWPE and Carbon Black

2019 ◽  
Vol 14 (2) ◽  
pp. 60-69 ◽  
Author(s):  
A. V. Markov ◽  
A. S. Chizhov
Keyword(s):  
Carbon Black ◽  
Heat Resistance ◽  
Elevated Temperatures ◽  
Average Particle Size ◽  
Cross Linking ◽  
Average Particle ◽  
Thermal Coefficient ◽  
Electrically Conductive ◽  
Pressing Method ◽  
Conductive Materials

Electrically conductive composites based on high density polyethylene (HDPE) / ultrahigh molecular weight polyethylene (UHMWPE) blends filled with carbon black were studied. The work is a part of the research of electrically conductive materials for the manufacture of self-regulating polymer heaters. In this work, the authors investigated composites based on HDPE/UHMWPE (molecular mass of ~ 7 million) blends filled with carbon black (average particle size ~ 20 nm). The goal of the work was to obtain a self-regulating electrically conductive polymer material with optimal thermoelectric characteristics and high heat resistance. It was shown that the effect of adding UHMWPE to the HDPE/carbon black composites on the thermoelectric behavior of the resulting material was similar to cross-linking. This reduced the undesirable effect of the negative thermal coefficient (NTC) of the electrical resistance. In addition, the heat resistance of the material at elevated temperatures was increased. This makes it possible to exclude the radiation or chemical cross-linking in the manufacture of self-regulating polymer heating elements. The rheological, mechanical and thermoelectric properties of HDPE/carbon black composites modified with UHMWPE were also studied. It was found that a diffusion interphase layer with a reduced fluidity in the melt of HDPE/UHMWPE blends was formed. It was established that self-regulating composites containing 30–40% of UHMWPE had the best operational properties. We can recommend the methods of extrusion and injection molding for the processing of HDPE/carbon black composites mixed with 30% UHMWPE, and the pressing method in case of UHMWPE content of 40%. The ability of the composites to be molded is sharply reduced at higher contents of UHMWPE.

scholarly journals FORMULATION AND EVALUATION OF DOXORUBICIN CONTAINING NANOGELS FOR DELIVERY TO CANCER CELLS

2018 ◽  
Vol 8 (5) ◽  
pp. 178-183
Author(s):  
Manish Kumar ◽  
Hemant K. Sharma
Keyword(s):  
Average Particle Size ◽  
Gellan Gum ◽  
Cross Linking ◽  
Average Particle ◽  
Scanning Calorimetry ◽  
Green Method ◽  
X Ray ◽  
Oppositely Charged ◽  
Chemical Cross Linking

The objective of this study is to prepare nanogels were prepared via charged gellan gum. It was prepared by in situ cross linking reaction between two oppositely charged materials by green method without use of chemical cross linking agents. The prepared nanogels were characterized by Dynamic light scattering, scanning electron microscopy, differential scanning calorimetry and X- Ray diffractometry. The prepared formulation had average particle size of 226 nm with polydispersity index of 0.3. The doxorubicin loaded nanogel demonstrated sustained release for 20 h. The prepared nanogels were hemocompatible and cyctocompatible as revealed by hemocompatibility and MTT assay respectively. All results confirmed that these nanogels can be used for cancer treatment. Keywords: Nanogel, Chitosan, Gellan gum, Doxorubicin, Cancer.

ER Properties of a Suspension of Polymer Graft Carbon Black Particles

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1682-1688
Author(s):  
Masayoshi Konishi ◽  
Teruhisa Nagashima ◽  
Yoshinobu Asako
Keyword(s):  
Shear Stress ◽  
Carbon Black ◽  
Electric Field ◽  
Silicone Oil ◽  
Average Particle Size ◽  
Average Particle ◽  
Zero Field ◽  
Average Value ◽  
Time Period ◽  
Micron Size

We newly developed ER particles with sub-micron size. The particle was polymer graft carbon black (GCB1) composed of carbon black particles and a polymer. The average particle size of GCB1 was found to be 81 nm. An ER suspension (ER1) was obtained by mixing GCB1 (30 wt%) with silicone oil (70 wt%). The ER1 showed excellent dispersion stability. Further, GCB1 particles did not settle under centrifuging at 9000G. The zero-field viscosity was 80 mPa·s at 25°C. The kinetic friction coefficient of ER1 was 0.15, while that of the silicone oil used was 0.23. When the electric field of 3 kV/mm (AC 1000 Hz) at the temperature of 25°C and the shear rate of 700 s -1 was applied to ER1, the shear stress of 116Pa was induced. The induced shear stress did not change for a long period of time period. In the temperature range between 25 and 150°C the induced shear stress and the current density were almost constant at any electric field. When 3 kV/mm (AC 50Hz) at 25°C and 700s-1 was applied to ER1, the shear stress of 88Pa was induced but the deviation of the induced shear stress from the average value was pluses and minuses 3 Pa.

Dodecane Decomposition in a Radio-Frequency (RF) Plasma Reactor

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
Laura Merlo-Sosa ◽  
Gervais Soucy
Keyword(s):  
Carbon Black ◽  
Plasma Reactor ◽  
Average Particle Size ◽  
Plasma Temperature ◽  
Experimental Results ◽  
Rf Plasma ◽  
Average Particle ◽  
Statistical Experimental Design ◽  
Operational Conditions ◽  
Carbon Molecules

The research outlined here includes a study of the production of carbon black (CB) in an inductive plasma reactor, using dodecane (C12H26) as the starting material. Thermodynamic and kinetic studies were carried out to predict the species concentrations likely to be obtained in the pyrolysis process at plasma temperatures. A thorough statistical experimental design was undertaken to investigate the influence of the different operational conditions such as: the feed rates of dodecane, the reactor pressure, the plate power applied to the plasma torch and the composition of the plasma gas, on the production of carbon black and gaseous acetylene-like compounds. Thermodynamic and kinetic models were compared with experimental results, a kinetic reaction model best representing the experimental results. Morphological analysis of the solid product using Transmission Electron Microscopy (TEM) indicates that a high plasma temperature is the most important factor affecting the final morphology of the carbon black formed during the reaction. Carbon black with average particle size of 10-30 nm and specific surface of 130 m2/g was obtained. Morphological analyses also demonstrated the presence of new structures ranging from carbon black to fullerenes and including certain “graphitized” carbon molecules.

scholarly journals The effect of gamma radiation on the ageing of sulfur cured NR/CSM and NBR/CSM rubber blends reinforced by carbon black

2009 ◽  
Vol 15 (4) ◽  
pp. 291-298 ◽  
Author(s):  
Gordana Markovic ◽  
Milena Marinovic-Cincovic ◽  
Vojislav Jovanovic ◽  
Suzana Samardzija-Jovanovic ◽  
Jaroslava Budinski-Simendic
Keyword(s):  
Carbon Black ◽  
Average Particle Size ◽  
Accelerated Ageing ◽  
Average Particle ◽  
Aromatic Rings ◽  
Rubber Blends ◽  
Rubber Blend ◽  
Infrared Measurements ◽  
Elastomeric Materials ◽  
Elastomeric Composites

In this work the effect of the ?-radiation dose on ageing of carbon black reinforced elastomeric materials was studied. The compounds based on natural rubber/chlorosulfonated rubber blend (NR/CSM) and butadiene acrylonitrile rubber/chlorosulfonated rubber blend (NBR/CSM) (50:50, w/w) with different loadings (0, 20, 40, 50, 60, 80 and 100 phr) of the filler with the average particle size of 40 nm were cured by sulfur. The obtained elastomeric composites were subjected to radiation doses (100, 200, 300 and 400 kGy) in the presence of oxygen. The changes of material mechanical properties were estimated after radiation accelerated ageing. By using Fourier transform infrared measurements (ATR-FTIR) it was assessed that after exposure to doses of 100 kGy alcohols, ethers, lactones, anhydrides, esters and carboxylic acids are formed in materials. The formation of shorter polyene sequences and aromatic rings in aged samples are assumed on the basis of the obtained spectra.

Fabrication and Strength Properties of LPS-SiC Ceramics

2005 ◽  
Vol 287 ◽  
pp. 183-188 ◽  
Author(s):  
Yi Hyun Park ◽  
Dong Hyun Kim ◽  
Han Ki Yoon ◽  
Akira Kohyama
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Average Particle Size ◽  
Process Temperature ◽  
Average Particle ◽  
Pressing Method ◽  
Temperature And Pressure ◽  
Sic Composites

SiC materials have been extensively studied for high temperature components in advanced energy system and advanced gas turbine. SiCf/SiC composites are promising for various structural materials. But, high temperature and pressure lead to the degradation of the reinforcing fiber during the hot pressing. Therefore, reduction of the process temperature and pressure is key requirements for the fabrication of SiCf/SiC composites by hot pressing method. In the present work, monolithic LPS-SiC was fabricated by hot pressing method at various temperatures. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. Compositions of sintering additives were Al2O3 / Y2O3 = 0.7 and 1.5 (wt.%). Monolithic LPS-SiC was evaluated in terms of sintering density, micro-structure, flexural strength, elastic modulus and so on. Sintered density, flexural strength and elastic modulus of fabricated LPS-SiC increased with increasing the process temperature. Particularly, relative density of LPS-SiC fabricated at 1820oC with additive composition of Al2O3/Y2O3=1.5(wt.%) was 95%. Also, flexural strength and elastic modulus were 900MPa and 220GPa, respectively. In the fracture surface of this specimen, the size and shape of SiC grains grew up and changed. Also, tortuous crack paths and occurrence of interfacial debonding were observed.

Effect of Poly(Vinyl Pyrrolidone) on Dispersing Carbon Black Particles

2013 ◽  
Vol 796 ◽  
pp. 432-436
Author(s):  
Xia Yuan
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Carbon Black ◽  
Ultrasonic Method ◽  
Aqueous Media ◽  
Average Particle Size ◽  
Sodium Dodecyl ◽  
Vinyl Pyrrolidone ◽  
Average Particle ◽  
Poly Vinyl Pyrrolidone

The effects of poly (vinyl pyrrolidone)(PVP) on dispersing carbon black (CB) particles were investigated by measuring Z-average particle size, Zeta potential and centrifugal stability of CB dispersions. Addition of PVP in a dispersing medium significantly reduces the size of suspended CB particles, especially in water. The dispersing efficiency of PVP was found to have been enhanced by adding an anionic surfactant, sodium methylenedinaphthalene disulphonate (NNO) in the aqueous media. The particle size of CB dispersed with PVP and NNO was 175.7 nm, significantly smaller than that dispersed with PVP and sodium dodecyl sulfate (SDS). The performance of PVP-encapsulated CB particles and that of PVP-adsorbed CB particles were also compared. The particle size and Zeta potential of PVP-encapsulated CB particles were similar to those of PVP-adsorbed CB particles using ultrasonic method, but the centrifugal stability of PVP-encapsulated CB dispersions was significantly improved. The relative absorbency of PVP/CB dispersions was increased from 42.0% to 63.7%. However, the PVP-encapsulated layer can be destroyed by prolonged ultrasonic treatment because the ultrasound over a long period of time can not only break up the flocculation bridge in the crosslinking matrix of PVP, but also flake off the PVP shells on the surface of CB particles.

scholarly journals Tenofovir Alafenamide Fumarate Microspheres, Process Parameters for Enhanced Permeability and Liver Targeting

2021 ◽  
pp. 187-196
Author(s):  
K. Sudhamani ◽  
B. Jeevan Jyothi
Keyword(s):  
Encapsulation Efficiency ◽  
Ex Vivo ◽  
Average Particle Size ◽  
Cross Linking ◽  
Average Particle ◽  
Class Iii ◽  
Ftir Studies ◽  
Ex Vivo Permeation ◽  
Permeation Studies ◽  
Tenofovir Alafenamide

Aims: Chronic hepatitis B (CHB) infection is a serious global health problem and one of the main causes of chronic liver disease, cirrhosis. Tenofovir Alafenamide Fumarate (TAF) is a prodrug of Tenofovir, a nucleotide analogue with limited oral bioavailability. TAF is considered to be a BCS Class III substance (high solubility, low permeability). The aim of the study was to develop the Tenofovir Alafenamide Fumarate (TAF) microspheres to improve permeability. Study design: Preparation and Evaluation of Microspheres. Place and Duration of Study: Department of pharmaceutics, Mallareddy Institute of Pharmaceutical Sciences, Affiliated to JNTUH, Hyderabad, Telangana, India, between January 2018 and June 2019. Methodology: TAF loaded chitosan microspheres were prepared by emulsion cross linking method using glutaraldehyde as cross-linking agent. The prepared microspheres were characterized by morphology, size distribution, encapsulation efficiency. The permeability study was evaluated by Ex-vivo permeation studies. The optimized formulation was subjected to FTIR studies to examine the Drug Excipient Compatibility. Results: Scanning Electron Microscopy (SEM) studies indicated that the microspheres are spherical in shape. The optimized formulation has average particle size of 11.00 ± 0.05 µm, the encapsulation efficiency 68 ± 0.04% and the percentage (%) yield of 94%. FTIR studies indicated that the drug and polymer are compatable with each other. In Ex-vivo permeation studies of optimized formulation 80% of drug was permeated with in 60 min. Conclusion: TAF microspheres could improve the absorption by increasing the permeability.

Carbon Black in Rubber Compounding

1941 ◽  
Vol 14 (1) ◽  
pp. 98-112 ◽  
Author(s):  
D. Parkinson
Keyword(s):  
Particle Size ◽  
Carbon Black ◽  
Fine Particle ◽  
Average Particle Size ◽  
Average Particle ◽  
Small Particles ◽  
Surface Development ◽  
Fine Particle Size ◽  
Filler Reinforcement ◽  
Methods Of Measurement

Abstract The mechanism of filler reinforcement has not yet been fully explained, but there is general agreement that an important, probably the most important, factor is the enormous surface development between the rubber and filler due to the fine particle size of the filler. Explanations have been attempted to show how small particles can cause reinforcement, but a complete theory of the phenomenon which accounts for all the facts is still awaited. Particle size oj carbon blacks.—A knowledge of this property is important in an understanding of the mechanism of reinforcement by carbon black. Because of the difficulty of distinguishing between ultimate particles and compact aggregates, and because the particles themselves are too small to be resolved in an ordinary microscope, the usual microscopical methods of measurement are inapplicable. Ultramicroscopical methods have been used with some success, the results obtained by the method of Gehman and Morris being probably the most reliable. These authors quote an average particle size of 61µµ for a sample of a standard rubber gas black (Micronex). The figures given for P-33 black, Shawinigan acetylene black and Thermatomic black are 159µµ, 130µµ and 1120µµ, respectively.

Finishing of Silk Textile with Fluorinated Polyacrylate Latex and the Effect of Silicone Cross-Linking Bond in Copolymer on Hydrophobicity and Lipophobicity

2013 ◽  
Vol 796 ◽  
pp. 360-363 ◽  
Author(s):  
Liang Shan ◽  
Zhan Xiong Li ◽  
Yan Xu ◽  
Lu Cai ◽  
Xiong Zang ◽  
...  
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Narrow Particle Size Distribution ◽  
Cross Linking ◽  
Average Particle ◽  
Silk Fabric ◽  
Emulsion Copolymerization ◽  
Fluorinated Polyacrylate ◽  
Level 3 ◽  
Textile Finishing

The lightly cross-linked fluorinated polyacrylate latex was synthesized by emulsion copolymerization, in which fluorine containing acrylate, butyl acrylate (BA) and organosiloxane containing bisacrylate were used as monomers. The fluorine containing co-polymeric emulsion was obtained with narrow particle size distribution and the average particle size to be about 130 nm. The emulsion with and without addition of cross-linking agent was applied on silk textile finishing. The result shows that, treating with the emulsion without cross-linking agent, the water-and oil-repellency of silk fabric reached level 3-4 and level 3, respectively, and the contact angle was up to 133.5°. After addition of cross-linking agent, the emulsion can afford the silk fabric with better water-and oil-repellency of level 4 and level 3-4, respectively. The improvement of water-and oil-repellency can probably be attributed to the lightly cross-linking structure of fluoropolymer, the latter resulted in more dense film on the surface of silk fabric after finishing.

The Mechanism of Reënforcement of Elastomers by Pigments

1948 ◽  
Vol 21 (3) ◽  
pp. 667-681 ◽  
Author(s):  
Leonard H. Cohan
Keyword(s):  
Calcium Carbonate ◽  
Carbon Black ◽  
Volume Concentration ◽  
Particle Diameter ◽  
Cross Linking ◽  
Average Particle ◽  
Average Particle Diameter ◽  
A Value ◽  
Synthetic Rubber ◽  
Similar Equation

Abstract Modulus appears to be independent of average particle diameter. With respect to the dependence of modulus on loading, calcium carbonate pigments which are symmetrical follow the equation derived by Guth and Gold for the relation between modulus and volume concentration of symmetrical inelastic particles. Up to about 80 parts by weight loading, HMF black follows a similar equation derived for rod-shaped particles, assuming a value of six for the ratio of the length to the diameter of the particles. The agreement with these theoretical equations is surprisingly good, and holds out the eventual possibility of calculating modulus over a wide loading range from tests at a single loading. Hardness and plasticity increase with loading in qualitative agreement with the equations. The behavior of modulus as a function of loading and average particle diameter of pigments indicates that vulcanized natural or synthetic rubber is not adsorbed in appreciable quantities or with sufficient force to be rendered inelastic at the surface of either calcium carbonate or carbon black pigments. Qualitative predictions based on the hypothesis that tensile strength is a measure of the force required to separate rubber chains from each other rather than to break rubber chains, and that pigment particles act as cross-linking agents holding the chains together, are in agreement with the behavior of calcium carbonate and carbon black pigments of widely different surface area over a considerable loading range.

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