scholarly journals Space Charge Property of Polyethylene/Silica Nanocomposites at Different Elongations

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Can Wang ◽  
Youyuan Wang ◽  
Peng Fan ◽  
Ruijin Liao
Keyword(s):  
Particle Size ◽  
Space Charge ◽  
Dipole Model ◽  
Particle Sizes ◽  
Test Results ◽  
Silica Nanocomposites ◽  
Induced Dipole ◽  
Interface Characteristics ◽  
Space Charge Distribution ◽  
Charge Property

This paper prepares polyethylene/silica nanocomposites with concentrations of 3 wt% and 5 wt% by using silicon dioxide (SiO2) nanopowder (nanosilica) with particle sizes of 15 and 50 nm. Samples whose elongations are 3%, 6%, and 10% are prepared. Pulsed electroacoustic technique is applied to evaluate the space charge distribution in samples. Test results show that homocharge near electrodes is generated in the polyethylene/silica nanocomposites. Nanocomposites with a nanoparticle concentration of 3 wt% and particle size of 15 nm suppress the accumulation of space charge effectively. The amount of space charge in the samples increases with the increase in elongation. At an elongation of 10%, packet-like space charge is generated in polyethylene/silica nanocomposites with the concentration of 5 wt% and particle sizes of 15 and 50 nm. The packet-like space charge in nanocomposites whose particle size is 50 nm is more obvious than that in nanocomposites whose particle size is 15 nm. The experiment results are explained by applying interface characteristics, dipole model, and induced dipole model.

Effects of Sand Particle Size and Gradation on Strength of Reactive Powder Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 208-211 ◽  
Author(s):  
Tao Ji ◽  
Bao Chun Chen ◽  
Yi Zhou Zhuang ◽  
Feng Li ◽  
Zhi Bin Huang ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Strength Test ◽  
Reactive Powder Concrete ◽  
Sand Particle ◽  
Particle Sizes ◽  
Test Results ◽  
Sand Mixture ◽  
Different Types ◽  
Reactive Powder

After modification, Toufar model was used to calculate the packing degrees of sand mixtures with different particle sizes. For four gradations of sands, the weight ratios of different types of sands with different size ranges, which achieve maximum packing degrees, have been obtained using the modified Toufar model. A strength test of reactive powder concretes (RPCs) with the four gradations of sands was reported. The test results show that the strength of RPC is related to both the maximum grain size and the packing degree of sand mixture. The smaller maximum grain size and larger packing degree of sand mixture can achieve the higher strength of RPC.

Effect of Particle Sizes on Rate Sensitivity and Dynamic Mechanical Properties of Polypropylene/Silica (PP/Sio2) Nanocomposites

2011 ◽  
Vol 364 ◽  
pp. 181-185 ◽  
Author(s):  
Firdaus Omar Mohd ◽  
Md Akil Hazizan ◽  
Zainal Arifin Ahmad
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Strain Rate ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Dynamic Mechanical Properties ◽  
Particle Sizes ◽  
Rate Condition ◽  
Dynamic Mechanical ◽  
Silica Nanocomposites

Filler-related characteristic such as particle size, shape and geometry are essential factors that need to be considered during the evaluation of the material’s performance especially in the area of particle filled composites. However, there is limited number of works are reported on this particular issue under high strain rate condition. Based on this concern, the paper presents an experimental results on the effect of particle sizes towards rate sensitivity and dynamic compressive properties of polypropylene/silica nanocomposites across strain rate from 10-2to 10-3s-1. The composite specimens were tested using universal testing machine for static loading and a compression split Hopkinson pressure bar apparatus for dynamic loading. Results show that, the stiffness and strength properties of polypropylene/silica nanocomposites were affected by the size of silica particles. However, the magnitudes of changed are somehow different between micro and nanosizes. On the other hand, particle size also plays a major contribution towards sensitivity of the polypropylene/silica nanocomposites where the smaller the reinforcement sizes, the less sensitive would be the composites. Overall, it is convenience to say that the particle size gives significant contribution towards rate sensitivity and dynamic mechanical properties of polypropylene/silica nanocomposites.

FLUID FLOW AND FALLING BALL EXPERIMENTS IN ER FLUIDS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2823-2833 ◽  
Author(s):  
R. N. ZITTER ◽  
T. J. CHEN ◽  
X. ZHANG ◽  
R. TAO
Keyword(s):  
Fluid Flow ◽  
Electric Fields ◽  
Electrorheological Fluid ◽  
Dipole Model ◽  
Particle Sizes ◽  
Constant Flow Rate ◽  
Particle Chain ◽  
Induced Dipole ◽  
Series Of Experiments ◽  
Er Fluids

The ability of the induced dipole–dipole model to predict various properties of an electrorheological fluid is tested in a series of experiments: the deformation of a single particle chain under fluid flow, the velocity of a falling ball at various electric fields, particle sizes, and concentrations, and flow valves operating at either constant pressure differential or constant flow rate. Analyses of these rather different experimental situations show that with proper application, the induced dipole model can give a fairly accurate description of observed characteristics.

Effect of Crumb Rubber Particle Size and Content on Properties of Crumb Rubber Modified (CRM) Asphalt

2011 ◽  
Vol 99-100 ◽  
pp. 955-959 ◽  
Author(s):  
Wei Dong Cao ◽  
Shu Tang Liu ◽  
Xin Zhuang Cui ◽  
Xiao Qing Yu
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Rubber Particle ◽  
Crumb Rubber ◽  
Particle Sizes ◽  
Test Results

Effects of crumb rubber of different particle sizes (20mesh, 40mesh, 60mesh, 80mesh and120mesh) and contents (10%, 15% and 20% by weight of the total of CRM asphalt) on the properties of CRM asphalt and change rule of performance of CRM asphalt with reaction temperature and time were studied in laboratory. The results indicate that CRM asphalt has the best performance when the particle size of crumb rubber used is 80 mesh and the content is 15%. The performance of CRM asphalt is strongly depended on reaction temperature and time. When reaction temperature is higher than 200°C and time more than 60 minutes, the viscosity of CRM asphalt significantly decline with reaction temperature rising and time delaying. The performance of CRM asphalt starts aging when reaction time more than 4 hours at high temperature. Based on test results, some suggestions for production and application of CRM asphalt are put forward.

Investigation of Space Charge Distribution of MgO/XLPE Composites Depending on Particle Size of MgO as Inorganic Filler

2013 ◽  
Vol 481 ◽  
pp. 108-116 ◽  
Author(s):  
Dae Sung Kim ◽  
Dong Hyun Lee ◽  
Yoon Jin Kim ◽  
Jin Ho Nam ◽  
Son Tung Ha ◽  
...  
Keyword(s):  
Particle Size ◽  
Space Charge ◽  
Volume Ratio ◽  
Acoustic Method ◽  
Inorganic Filler ◽  
Charge Dynamics ◽  
Dispersion Degree ◽  
Space Charge Distribution ◽  
Dilution Volume ◽  
Dc Stress

MgO/XLPE composites, composed of micro-and nanosized MgO material having different particle size as inorganic filler and cross linked polyethylene (XLPE), were prepared and investigated to the space charge dynamics of these composites for high voltage DC insulation. Added MgO material, having 50nm to 1μm in size, were synthesized from the calcination of Mg (OH)2nanoplatelets which was controlled by potassium content in Mg (OH)2, varying the dilution volume ratio of distilled water/ Mg (OH)2suspension. MgO/XLPE composites were obtained by thoroughly mixing LDPE and dicumyl peroxide (DCP) as the cross-linking agent and silane modified MgO before kneading to enhance the dispersion degree of the composites. The space charge distributions of the composites were observed by controlling the particle size and content of a dispersed MgO in XLPE matrix. To prevent the breakdown under high DC stress, it was found that the reduction of space charge of MgO/XLPE composite depends upon the smaller size of MgO particle and the its content above 0.5 phr (per hundred part of resin, wt%). MgO material and MgO/ XLPE composites were characterized with TEM, XRD, BET, ICP, and the space charge properties of the composites were measured by a pulsed electro-acoustic method (PEA).

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

Space Charge Distribution Measurement in FEP Film Irradiated by Proton

2020 ◽  
Vol 140 (10) ◽  
pp. 504-505
Author(s):  
Kaisei Enoki ◽  
Ushio Chiba ◽  
Hiroaki Miyake ◽  
Yasuhiro Tanaka
Keyword(s):  
Space Charge ◽  
Charge Distribution ◽  
Distribution Measurement ◽  
Space Charge Distribution

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

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