THE HEATS OF SOLUTION AND SPECIFIC HEATS OF RHOMBIC SULPHUR IN CARBON DISULPHIDE: THE SURFACE ENERGY OF SOLID RHOMBIC SULPHUR

1935 ◽  
Vol 13b (5) ◽  
pp. 280-288 ◽  
Author(s):  
A. R. Williams ◽  
F. M. G. Johnson ◽  
O. Maass
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Carbon Disulphide ◽  
Heat Of Solution ◽  
Specific Heats ◽  
Heats Of Solution

The heats of solution of rhombic sulphur in carbon disulphide were measured over the concentration range 6 to 17% of sulphur and at 20° and 25 °C., and the specific heats of these solutions were calculated. The apparatus designed for these measurements is described. By measuring the heat of solution of finely divided sulphur and its particle size, the surface energy of solid rhombic sulphur is estimated.

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.

scholarly journals Surface energy of nanoparticles – influence of particle size and structure

2018 ◽  
Vol 9 ◽  
pp. 2265-2276 ◽  
Author(s):  
Dieter Vollath ◽  
Franz Dieter Fischer ◽  
David Holec
Keyword(s):  
Molecular Dynamics ◽  
Particle Size ◽  
Surface Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Definition Of ◽  
Dynamics Simulations ◽  
Classical Thermodynamics ◽  
A Minor

The surface energy, particularly for nanoparticles, is one of the most important quantities in understanding the thermodynamics of particles. Therefore, it is astonishing that there is still great uncertainty about its value. The uncertainty increases if one questions its dependence on particle size. Different approaches, such as classical thermodynamics calculations, molecular dynamics simulations, and ab initio calculations, exist to predict this quantity. Generally, considerations based on classical thermodynamics lead to the prediction of decreasing values of the surface energy with decreasing particle size. This phenomenon is caused by the reduced number of next neighbors of surface atoms with decreasing particle size, a phenomenon that is partly compensated by the reduction of the binding energy between the atoms with decreasing particle size. Furthermore, this compensating effect may be expected by the formation of a disordered or quasi-liquid layer at the surface. The atomistic approach, based either on molecular dynamics simulations or ab initio calculations, generally leads to values with an opposite tendency. However, it is shown that this result is based on an insufficient definition of the particle size. A more realistic definition of the particle size is possible only by a detailed analysis of the electronic structure obtained from initio calculations. Except for minor variations caused by changes in the structure, only a minor dependence of the surface energy on the particle size is found. The main conclusion of this work is that surface energy values for the equivalent bulk materials should be used if detailed data for nanoparticles are not available.

The dependence of the surface energy of regular clusters and small crystallites on the particle size

1988 ◽  
Vol 23 (9) ◽  
pp. 1153-1159 ◽  
Author(s):  
E. Müller ◽  
W. Vogelsberger ◽  
H.-G. Fritsche
Keyword(s):  
Particle Size ◽  
Surface Energy

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.

scholarly journals The study of the process of physic-chemical destruction of coal by the method of physical modeling

2019 ◽  
Vol 109 ◽  
pp. 00054
Author(s):  
Serhii Makeiev ◽  
Serhii Andreiev ◽  
Hennadii Ryzhov
Keyword(s):  
Particle Size ◽  
Hydrochloric Acid ◽  
Surface Energy ◽  
Physical Modeling ◽  
Laboratory Experiments ◽  
Physical Simulation ◽  
Treated Area ◽  
Chemical Destruction ◽  
Clay Rocks ◽  
Physical And Chemical

One of the possible ways of physic-chemical destruction (PCD) of coal was considered. It is established that condition of the realization of a principle possibility of spontaneous dispersion of coal is to reduce its surface energy by 40-60 J/m2. Laboratory experiments to study the PCD of coal in different liquids were conducted. According to the results, kinetic curves of swelling coal in them transition D-G stamps is presents. It was established that the most intensive physical and chemical destruction of the coal to a particle size from tenths to tens of millimeters occurs in solutions of methylamine and hydrochloric acid. The most severe swelling of the coal was noted in those environment as well. The intensity of swelling is not significantly associated with the characteristics of wetting. The influence of various effects on the PCD parameters of coal was studied by physical simulation. The total time the chemical destruction of coal on the treated area was calculated. It was proposed method PCD for coals occurring in the clay rocks of various stages of catagenesis.

Fine Particles: Science and Technology

MRS Bulletin ◽  
1989 ◽  
Vol 14 (12) ◽  
pp. 18-22 ◽  
Author(s):  
Egon Matijević
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Chemical Composition ◽  
Surface Energy ◽  
Total Energy ◽  
Everyday Life ◽  
Fine Particles ◽  
Simple Consideration ◽  
Effect Of Particle Size ◽  
Properties Of Materials

Some readers may wonder about the reasons for having two issues focus on fine particles. Hopefully, this introduction and the articles to follow will offer the necessary justification.It is fully expected by everybody, professional or laie, that the properties of matter will change if its chemical composition is altered. It is less frequently recognized that many characteristics of materials can be dramatically affected by varying dimensions, yet countless examples in everyday life clearly demonstrate such phenomena. Consider water in droplet form. Driving in rain creates little problem, providing the car has working windshield wipers. In contrast fog, which consists of droplets of much smaller size, represents one of the major hazards in transportation. Obviously, the optical properties of the same matter have greatly altered with diminution. In another example, it is well known that finely dispersed carbon is an excellent adsorbent, a property used in gas masks and in many industries as a purifying agent. Large-sized lumps of such carbon would be useless in these applications.The effect of particle size on properties of materials can be readily understood from a simple consideration. The total energy of any System, (Etot), consists of two contributions, the internai energy, Ei, and the surface energy, Ei.

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