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.

Oxygen-Enriched Combustion Characteristics of Lignite: A Case Study of the Pingzhuang Lignite from Inner Mongolia, China

2012 ◽  
Vol 550-553 ◽  
pp. 2868-2872
Author(s):  
Xiang Yun Chen ◽  
Yong Feng Zhang ◽  
Qian Cheng Zhang ◽  
Jie Bai ◽  
Fei Wu
Keyword(s):  
Particle Size ◽  
Oxygen Concentration ◽  
Volume Fraction ◽  
Particle Sizes ◽  
Temperature Zone ◽  
Thermogravimetric Method ◽  
Combustion Experiment ◽  
Lower Temperature ◽  
Lower Temperature Zone

Combustion curves of lignite samples from China in four different particle sizes and Oxygen-enriched condition were analyzed using non-isothermal thermogravimetric method. The lignite samples separated into -150+100 μm, -100+75 μm, -75+50 μm, and -50μm sizes. Combustion profiles shift to lower temperature zone as particle size decrease. Combustion profiles have little difference when the particle size below 100 μm in oxygen atmosphere; Oxygen-enriched combustion experiment were carried out in O2/N2 mixture atmospheres with the volume fraction of oxygen was 21%, 30%, 40%, 50%, 60% and 70%, respectively. As oxygen concentration increase profiles shift to lower temperature zone. and gets the proper range of oxygen concentration is about 50%.

Preparation, ignition, and combustion of mechanically alloyed Al-Mg powders with customized particle sizes

2013 ◽  
Vol 1521 ◽  
Author(s):  
Yasmine Aly ◽  
Vern K. Hoffman ◽  
Mirko Schoenitz ◽  
Edward L. Dreizin
Keyword(s):  
Particle Size ◽  
Ignition Delay ◽  
Pure Aluminum ◽  
Particle Morphology ◽  
Combustion Characteristics ◽  
Particle Sizes ◽  
Mechanically Alloyed ◽  
Pressurization Rate ◽  
Improved Performance ◽  
Ignition And Combustion

ABSTRACTAdding aluminum to propellants, pyrotechnics, and explosives is a common way to boost their energy density. A number of approaches have been investigated that shorten aluminum ignition delay, increase combustion rate, and decrease the tendency of aluminum droplets to agglomerate. Previous work showed that particles of mechanically alloyed Al-Mg powders burn faster than similarly sized particles of pure aluminum. However, preparation of mechanically alloyed powders with particle sizes matching those of fine aluminum used in energetic formulations was not achieved. This work is focused on preparation of mechanically alloyed, composite Al-Mg powders in which both internal structures and particle size distributions are adjusted. Binary powders with compositions in the range of 50 - 90 at. % Al were prepared and characterized. Milling protocol is optimized to prepare equiaxial, micron-scale particles suitable for laboratory evaluations of their oxidation, ignition, and combustion characteristics. Quantitative particle size analyses are done using low-angle laser light scattering. Electron microscopy and x-ray diffraction are used to examine particle morphology and phase makeup, respectively. Combustion of aerosolized powder clouds is studied using a constant volume explosion setup. For all materials, ignition and combustion characteristics are compared to each other and to those of pure Al. Compositions with improved performance (i.e., shorter ignition delay and faster pressurization rate) compared to pure Al are identified.

Morphology Change in Cuprous Oxide Particle Synthesis with PVP: Effect of Reaction Temperature

2013 ◽  
Vol 873 ◽  
pp. 147-151
Author(s):  
Cheng Dong Wang ◽  
Ji Qian Wang
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Surface Energy ◽  
Reaction Temperature ◽  
Cuprous Oxide ◽  
Oxide Particle ◽  
High Energy ◽  
Red Shift ◽  
Reaction Condition ◽  
Lower Temperature

Cuprous oxides with different morphologies could be prepared by simply changing the reaction condition, such as the temperature. Here, we report the Cu2O morphological transforming from polyhedron to cube with the reaction temperature increasing from 35C to 65C. At lower temperature, the polyvinylpyrrolidone (PVP) working as a crystal modifier which decreases the surface energy of facets (111) and (110), thus these high energy facets appear in relative low temperature. Facets (111) and (110) gradually diminished along with temperature increasing, while facet (100) expanded. The morphology became into cube from polyhedron. Cu2O particles synthesized at 65C are larger than those at 35C. The UV-Vis extinction bands of the cuprous oxide synthesized in this research were red-shift with the increase of particle size.

Dynamic Hydrothermal Synthesis of Super-Low Density Xonotlite Thermal Insulation Materials from Industrial Quartz Powder

2017 ◽  
Vol 726 ◽  
pp. 569-575 ◽  
Author(s):  
Hong Zhi Yue ◽  
Xin Wang ◽  
Zan Zhong Yang ◽  
Chun Cheng Wei
Keyword(s):  
Particle Size ◽  
Thermal Insulation ◽  
Particle Morphology ◽  
Zirconium Oxychloride ◽  
Low Density ◽  
Particle Sizes ◽  
Quartz Powder ◽  
Insulation Materials ◽  
The Common ◽  
Very High

Xonotlite was synthesized by dynamic hydrothermal methode with industrial quartz powder as the siliceous materials and calcium hydroxide derived from hydration of calcined calcium carbonate as calcareous material.This paper focused on the influence of particle size of the industrial quartz powder, the mass ratio of water and solid reactants (W/S) and additives on the product composition, apparent density and crystal morphology. The products were characterized by X-ray powder diffraction (XRD), scanning eletron microscope (SEM) and other analysis methodes. Results indicated that in a certain range to decrease particle sizes of quartz powder could improve the content of xonotlite under the help of potassium hydroxide and zirconium oxychloride, the content of xonotlite could reach 99.5% when the particle size of quartz powder decrease to 4.65um no need to the common level of below 1 um in some literature. The product had a very high xonotlite content and perfect particle morphology when the ratio of W/S was controled over 30%; under the help of strontium ions and zirconium ions xonotlite fiber became significantly slimmer with a greater ratio of length to diameter,which was easier to obtain super-low density xonotlite thermal insulation materials.

On the Sintering Activation Energy of α-Al2O3

2008 ◽  
Vol 368-372 ◽  
pp. 686-687 ◽  
Author(s):  
Wei Quan Shao ◽  
Shaou Chen ◽  
Da Li ◽  
Ping Qi ◽  
Yong Wan ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Temperature Interval ◽  
High Purity ◽  
Powder Compact ◽  
Isothermal Condition ◽  
Particle Sizes ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Increasing Temperature

The sintering activation energy of high-purity alumina powders with different particle sizes was evaluated under non-isothermal condition. It was found that, during sintering, the activation energy for the lower temperature stage is higher than that for higher temperature stage. The value of the activation energies for the powder compact with larger particle size was higher than that for the powder compact with smaller particle size. If the selected temperature interval for calculation was narrow enough, the evaluated activation energy values varied with the increasing temperature continuously.

scholarly journals Effect of lignin-containing highly fibrillated cellulose on the adsorption behavior of an organic dye

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 6560-6576
Author(s):  
Zhongyu Yan ◽  
Caifu Yi ◽  
Jiawan Yang ◽  
Haizhu Ma ◽  
Lizheng Sha ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Organic Dyes ◽  
Nanofibrillated Cellulose ◽  
Organic Dye ◽  
Morphological Properties ◽  
Particle Sizes ◽  
Preparation Process ◽  
Key Factors ◽  
Final Performance

The morphological properties and particle size characteristics of micro- and nanofibrillated cellulose (NFC) and lignin-containing NFC (LNFC) produced by a microfluidizer processor were investigated. The effects mechanism of lignin-containing on the adsorption of NFC and the stable properties of organic dyes suspension were also studied. The results showed that the preparation process and final performance of NFC were affected by the key factors including lignin, homogenization pressure, and number of homogenization cycles. The increase in the homogeneity of the fibrillated cellulose was minor for the NFC samples, while LNFC samples showed a larger increase in the homogeneity of the particle size distribution. The influence of lignin was reflected both in improved fibrillation efficiency and in the final organic dye dispersion properties achieved by LNFC addition, primarily observed as deceased particle sizes and fibril dimensions. This study indicated that pollution-free dispersion of organic dyes can be realized through the application of lignin-containing NFC.

Effect of Surface Energy on the Wear Process

1964 ◽  
Vol 86 (2) ◽  
pp. 306-310 ◽  
Author(s):  
E. Rabinowicz ◽  
R. G. Foster
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Wear Particle ◽  
Particle Sizes ◽  
Wear Particles ◽  
Wear Process ◽  
External Variables ◽  
Particle Measurement ◽  
Effect Of Surface ◽  
Correct Size

It was previously shown that the size of loose wear particles formed during the sliding of two materials is equal to 60,000 Wab/P, where Wab is the surface energy of adhesion and p the penetration hardness. Experimental results are presented which show that the experimental particle sizes obtained with a few materials do indeed obey the theoretical relationship, and that the particle size is, as predicted, almost independent of such external variables as speed, time, geometry, and load, provided the load is not too great. Indeed, if particles of the wrong size are fed into the system, then they tend to be broken down or built up until the correct size is reached. However, changes of atmosphere and the use of lubricants, which alter the energy of adhesion, do have a marked influence on wear-particle size, and this fact suggests a possible use of wear-particle measurement to rate boundary lubricants. Other surface interaction phenomena which are governed by the W/p ratio are discussed, and it is suggested that the surface roughness generated during sliding is a function of this ratio.

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.

Nanostructured Polymetallic Powders to Create New Functional Materials on its Base

2015 ◽  
Vol 670 ◽  
pp. 49-54 ◽  
Author(s):  
Yuriy A. Zaharov ◽  
Valeriy M. Pugachev ◽  
Kseniya A. Datiy ◽  
Anna N. Popova ◽  
Anastasiya S. Valnyukova ◽  
...  
Keyword(s):  
Particle Size ◽  
Phase Diagrams ◽  
Spatial Organization ◽  
Functional Materials ◽  
Particle Morphology ◽  
Cloud Type ◽  
Synthesis Conditions ◽  
Micron Size ◽  
Common Nature ◽  
20 Nm

In the paper, the particle morphology is considered and the slices of phase diagrams of nanosystems agreeable to the synthesis conditions are constructed according to the data obtained earlier by authors, as well as new results of the study of nanostructured Fe-Co, Fe-Ni, Co-Ni, Fe-Co-Ni, Fe-Pt, Cu-Ni and Ni-Cd powders. It is found that all considered polymetallic systems have common nature of the particle size spatial organization, i.e., 7-20 nm nanocrystals (for different systems) form highly compact aggregates (40-100 nm) which put together into loose porous agglomerates (up to 200-250 nm) and then into unconsolidated micron size formation of cloud type. It is classified uncovered features of nanostructured polymetallic phase diagrams in comparison with phase diagrams of bulk systems. Magnetic properties of nanosystems are studied.

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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