scholarly journals Quantitative Analysis of Solubility Parameters and Surface Properties of Larch Bark Proanthocyanidins

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2800
Author(s):  
Siqi Chen ◽  
Jie Song ◽  
Liuping Du ◽  
Yanli Ma ◽  
Shixue Ren ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Molecular Dynamics Simulations ◽  
Polymer Composites ◽  
Surface Properties ◽  
Surface Acidity ◽  
Solubility Parameters ◽  
Interfacial Interactions ◽  
Ultraviolet Resistance ◽  
Dynamics Simulations

Quantitative characterization of the solubility parameters and surface properties of larch bark proanthocyanidins will lay the foundation for quantitative studies of the interfacial interactions of proanthocyanidin/polymer composites and will improve the compatibility of components, with important practical and scientific significance. Here, the solubility parameters of highly polymerized larch polymeric proanthocyanidins (LPPCs) and less highly polymerized larch oligomeric proanthocyanidins (LOPCs) were determined experimentally by inverse gas chromatography (IGC). These values were then compared with the solubility parameters obtained using molecular dynamics simulations. The experimentally measured solubility parameters of LPPCs and LOPCs (20.5 and 22.09 (J/m−3)0.5, respectively) were in good agreement with the solubility parameters determined by molecular dynamics simulations (20.57 and 22.35 (J/m−3)0.5, respectively. IGC was also used to experimentally determine the total surface energy, which includes the dispersive component of surface energy γsd  and the specific component of surface energy γssp, together with the surface acidity and basicity parameters of LPPCs and LOPCs at different temperatures. The surface properties of proanthocyanidins can be quickly and accurately evaluated by IGC, and both LPPCs and LOPCs were shown to be amphoteric materials. This study provides theoretical and technical support for the use of larch bark proanthocyanidins, which are non-toxic, renewable, and have good ultraviolet resistance, in the field of blending composites. The study also provides a reference for other studies on the interfacial interactions of wood fiber polymer composites.

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.

Tunable Gigahertz Oscillators of Gliding Incommensurate Bilayer Graphene Sheets

2013 ◽  
Vol 80 (4) ◽  
Author(s):  
Ming Luo ◽  
Zhuhua Zhang ◽  
Boris I. Yakobson
Keyword(s):  
Molecular Dynamics ◽  
Surface Energy ◽  
Molecular Dynamics Simulations ◽  
Friction Force ◽  
Function Theory ◽  
Bilayer Graphene ◽  
Atomistic Simulations ◽  
Graphene Sheets ◽  
Dynamics Simulations ◽  
Oscillation Frequencies

Oscillators composed of incommensurate graphene sheets have been investigated by molecular dynamics simulations. The oscillation frequencies can reach tens of gigahertz range and depend on the surface energy of the bilayer graphene and the oscillatory amplitude. We demonstrate the tunability of such an oscillator in terms of frequency and friction by its varying geometric parameters. Exploration of the damping mechanism by combining the autocorrelation function theory and the direct atomistic simulations reveals that the friction force is proportional to the velocity of oscillatory motion. The results should help optimize the design of graphene-based nanoelectromechanical devices.

scholarly journals Rouse mode analysis of chain relaxation in polymer nanocomposites

Soft Matter ◽  
2015 ◽  
Vol 11 (20) ◽  
pp. 4123-4132 ◽  
Author(s):  
Jagannathan T. Kalathi ◽  
Sanat K. Kumar ◽  
Michael Rubinstein ◽  
Gary S. Grest
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Polymer Composites ◽  
Polymer Nanocomposites ◽  
Large Scale ◽  
Mode Analysis ◽  
Dynamics Simulations

Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites.

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