scholarly journals Research on the Influence of Sodium Ion on Mechanism of Polymer Solution Viscosity Loss

2021 ◽  
Author(s):  
Chun’an Du ◽  
Xianya Zhang ◽  
Weiwei Chen ◽  
Peng Xu
Keyword(s):  
Polymer Solution ◽  
Molecular Conformation ◽  
Molecular Chain ◽  
Sodium Ion ◽  
Dynamics Simulation ◽  
Solution Viscosity ◽  
Spatial Network ◽  
Molecular Configuration ◽  
Polymer Microstructure ◽  
Scanning Electron

The researches on the influence of sodium ion on mechanism of polymer solution viscosity loss were conducted. Scanning electron microscopy was used to analyze the polymer microstructure. Molecular dynamics simulation was employed to reveal the influence of sodium ion on the polymer molecular configuration. The results shown: the polymer viscosity loss was more than 70% when the concentration of sodium ion was above 4000 mg/L. The results of microstructure and molecular conformation analysis indicated that the main reason of viscosity loss was the electrostatic attraction between sodium ion and negatively charged groups of polymer molecule chains, which cause compression of polymer molecular chain. The coil and shrinkage of polymer molecular chain led to the breakage of the spatial network structure of macromolecules.

Molecular Dynamics Studies on the Growth and Structural Properties of Hydrogenated DLC Films

2008 ◽  
Vol 373-374 ◽  
pp. 108-112
Author(s):  
Yu Jun Zhang ◽  
Guang Neng Dong ◽  
Jun Hong Mao ◽  
You Bai Xie
Keyword(s):  
Molecular Dynamics ◽  
Structural Properties ◽  
Impact Energy ◽  
Frictional Coefficient ◽  
Carbon Films ◽  
Dynamics Simulation ◽  
Diamond Surface ◽  
Hydrogen Atoms ◽  
Molecular Configuration ◽  
The Impact

The novel frictional properties of hydrogenated DLC (Diamond-like Carbon) films have been reported for nearly ten years. But up to now, researchers still haven’t known the exact mechanism resulting in the super-low frictional performance of hydrogenated DLC films. Especially they have little knowledge on the molecular configuration and structural properties of these kinds of films. In this paper, CH3 radicals with different impact energies are selected as source species to deposit DLC films on diamond (100) by molecular dynamics simulation. Results show hydrogenated DLC films can be successfully obtained when impact energy is in an appropriate scope that is no less than 20eV. The depositing processes involve impinging diamond surface and bonding procedure. Some atoms, instead of bonding with substrate atoms, fly away from the diamond surface. Only suitable impact energy can improve the growth of the film. Within 30eV to 60eV, the maximum deposition ratio is attained. In addition, when carbon atoms act as the deposition sources, the deposition ratio is relatively higher. Furthermore, the authors find that species with higher concentration of carbon atoms in deposition sources lead to a better deposition rate. Carbon atoms are more reactive than hydrogen atoms. Then the relative densities of DLC films are calculated. The density curves indicate that the structures of the films vary obviously as the impact energy augments. The average relative density is generally monotone increase with the increment of impact energy. The hybridization of carbon atoms greatly affects the properties of hydrogenated DLC films. The transition between sp2 and sp3 will result in the graphitization and reduce the frictional coefficient when DLC films are used as tribo-pair in friction.

scholarly journals Processing parameters for electrospinning poly(methyl methacrylate) (PMMA)/titanium isopropoxide composite in a pump-free setup

2018 ◽  
Vol 1 ◽  
pp. 27
Author(s):  
Leah Nyangasi ◽  
Dickson Andala ◽  
Charles Onindo ◽  
Alphonse Wanyonyi ◽  
Josphine Chepngetich
Keyword(s):  
Methyl Methacrylate ◽  
Polymer Solution ◽  
Solution Concentration ◽  
Titanium Isopropoxide ◽  
Processing Parameters ◽  
Solution Viscosity ◽  
Poly Methyl Methacrylate ◽  
Size And Morphology ◽  
Set Up ◽  
Almost All

Background: Electrospinning is a technique for producing nanofibers, useful in many fields of nanotechnology. The size and morphology of the nanofibers obtained depends on the polymer solution properties, the parameters of the equipment and the conditions of the surrounding. In almost all reported electrospinning set ups, a pump ,which regulates the flow of the polymer solution, has been included as one of the requirements. In this study, the effects of solution concentration, viscosity, voltage and the distance from the tip of the syringe to the aluminum collector on the morphology and diameters of poly(methyl methacrylate)(PMMA) fibers were investigated, using a pump-free electrospinning set up. Methods: Varied PMMA concentration (50 -120 mg/mL), voltage (10-18 kV) and distance (5 – 18 cm) of electrospinning were studied and the optimum electrospinning conditions identified.  PMMA/ titanium isopropoxide solution of ratio 1:2 was prepared, electrospun at optimized conditions (15 kV, 18 cm, Dichloromethane/Dimethylformamide 60:40) and the fibers obtained analyzed using a scanning electron microscope. Results: Solutions of PMMA whose concentrations were less than 50 mg/mL, produced beads on fibers, whereas those at ~ 100 mg/mL formed the best bead-free fibers of diameter 350±50 nm. The results showed a direct dependence of fiber diameter on the solution viscosity. Fibers of larger diameters were obtained when the distance from the tip of the syringe to the aluminum collector and voltage were increased but at higher distances (>18 kV) fewer fibers were collected. When the voltage was steadily increased, the fibers broadened and the diameters were non-uniform due to splaying and splitting. Increasing the distance between the pipette-tip and the collector from 10 to 18 cm resulted in reduced electric field which in turn yielded fewer fibers. Conclusions: The results obtained in a pump free set-up were comparable to those eletrospun in the presence of a pump.

Improvement of Morphology, Structure, and Thermal Properties of Electrospun PVA/RSF Fiber Mats by SiO2

2012 ◽  
Vol 184-185 ◽  
pp. 1017-1020 ◽  
Author(s):  
Yan Hua Liu ◽  
Li Xing Dai
Keyword(s):  
Thermal Properties ◽  
Silicon Dioxide ◽  
Solution Viscosity ◽  
Electrospun Fibers ◽  
Fiber Morphology ◽  
Fiber Mats ◽  
Hydrogen Bonding Interactions ◽  
Regenerated Silk Fibroin ◽  
Solution Conductivity ◽  
Scanning Electron

Poly(viny1 alcohol) (PVA)/regenerated silk fibroin (RSF)/silicon dioxide (SiO2) fiber mats were prepared by electrospinning of composite solutions. Fiber morphology was observed under a scanning electron microscope and effects addition of SiO2 was evaluated. Results showed that the obtained fibers exhibited a smooth outer surface, and the continuity was improved because of the different solution conductivity, solution viscosity and compatibility of PVA and RSF by the addition of 1.0 wt. % SiO2. It was found that both Si-O-C linkage and hydrogen bonding interactions were existed among SiO2, PVA, and RSF by FTIR spectroscopy. The addition of SiO2 also resulted in the decrease of crystallinity and increase of thermal properties of electrospun fibers, which were suggested as a result of enhanced compatibility and physical properties of PVA and RSF composite.

Implementation of an Efficient Algorithm for Virtual Prototyping of Dynamics of Molecular Conformation

2009 ◽  
Author(s):  
Shanzhong Shawn Duan ◽  
Andrew Ries
Keyword(s):  
High Frequency ◽  
Efficient Algorithm ◽  
Molecular Conformation ◽  
Molecular System ◽  
Molecular Model ◽  
Virtual Prototyping ◽  
Molecular Chain ◽  
Integration Step ◽  
Computational Performance ◽  
Macro Scale

This paper presents an O(N) algorithm and its preliminary computer simulation results for virtual prototyping of molecular systems with a simple chain structure. The algorithm is based on proper integration between an internal coordinate method (ICM) and a multibody molecular model. ICM method makes the use of recursive relations possible between two adjacent subsets within a molecular system. The multibody molecular model takes the benefits of freezing degrees of freedom of some lightly excited high frequency bonds. Because these high frequency bonds would force the use of very small integration step sizes, which severely limits the time scales for virtual prototyping of dynamics of molecular conformation over long periods of time. Thus a new multiscale model and efficient algorithm is produced to increase computational efficiency for virtual prototyping of dynamical behaviors of molecular confirmation. This paper will be initially directed towards introduction of the new model and algorithm. Then attention will be turned to the implementation of the algorithm at macro scale, which can be used to demonstrate the validity of the procedure and algorithm. Final focus will be turned to the implementation of the algorithm to a simple molecular chain at micro scale. The algorithm gives an O(N) computational performance for formation/solution of equations of motion for a molecular chain system.

scholarly journals A New Empirical Model for Viscosity of Sulfonated Polyacrylamide Polymers

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1046 ◽  
Author(s):  
Saeed Akbari ◽  
Syed Mohammad Mahmood ◽  
Hosein Ghaedi ◽  
Sameer Al-Hajri
Keyword(s):  
Polymer Solution ◽  
Oil Recovery ◽  
Empirical Model ◽  
Linear Regression Analysis ◽  
Polymer Concentration ◽  
Polymer Flooding ◽  
Solution Viscosity ◽  
Operational Variables ◽  
Reservoir Conditions ◽  
Sulfonated Polyacrylamide

Copolymers of acrylamide with the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid—known as sulfonated polyacrylamide polymers—had been shown to produce very promising results in the enhancement of oil recovery, particularly in polymer flooding. The aim of this work is to develop an empirical model through the use of a design of experiments (DOE) approach for bulk viscosity of these copolymers as a function of polymer characteristics (i.e., sulfonation degree and molecular weight), oil reservoir conditions (i.e., temperature, formation brine salinity and hardness) and field operational variables (i.e., polymer concentration, shear rate and aging time). The data required for the non-linear regression analysis were generated from 120 planned experimental runs, which had used the Box-Behnken construct from the typical Response Surface Methodology (RSM) design. The data were collected during rheological experiments and the model that was constructed had been proven to be acceptable with the Adjusted R-Squared value of 0.9624. Apart from showing the polymer concentration as being the most important factor in the determination of polymer solution viscosity, the evaluation of the model terms as well as the Sobol sensitivity analysis had also shown a considerable interaction between the process parameters. As such, the proposed viscosity model can be suitably applied to the optimization of the polymer solution properties for the polymer flooding process and the prediction of the rheological data required for polymer flood simulators.

POLYAMIDE/POLYESTERAMIDE BASED NANOFIBERS

2011 ◽  
Vol 04 (04) ◽  
pp. 365-368 ◽  
Author(s):  
LENKA MALINOVÁ ◽  
VÁCLAVA BENEŠOVÁ ◽  
DANIELA LUBASOVÁ ◽  
LENKA MARTINOVÁ ◽  
JAN RODA ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Aspect Ratio ◽  
Polymer Solution ◽  
High Aspect Ratio ◽  
Electrospinning Method ◽  
Microscopy Images ◽  
Scanning Electron

The formation of novel high aspect ratio nanofibers from polyesteramides based on ε-caprolactam and ε-caprolactone is reported. Nanofibers were prepared by the electrospinning method from polymer solution. Scanning electron microscopy images of nanofiber layers revealed that the diameter of fibers depended on the nature of the solvent or the mixture of solvents used and especially on the composition of polyesteramides.

Manufacturing and Evaluation of Porous PLA Nano/Micro Fibres

2016 ◽  
Vol 368 ◽  
pp. 146-149
Author(s):  
Eva Macajová
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Image Analysis ◽  
Polymer Solution ◽  
Process Parameters ◽  
Fibre Diameter ◽  
Solution Composition ◽  
Structure And Morphology ◽  
Spinning Process ◽  
Scanning Electron

This study is mainly focused on the study of pore size and shape, fibre diameter and also on the optimization of polymer solution composition and electrospinning parameters with respect to the final structure and morphology of PLA nano/microfibrous layers. The nano/microfibres were produced by electrospinning from the needle. Except the spinning process parameters, the morphology of nanofibrous layers can be also affected by the composition of the polymer solution and by the used solvents. Variations in technological process allows us to design the shape and form of nanofibrous structures upon request. The morphology of nano/microfibres was observed by scanning electron microscopy (SEM). Following image analysis and calculation enables the assessment of porosity contribution to the increase in micro/nanofibre surface area.

scholarly journals Study on Adsorption Characteristics of Sulfonate Gemini Surfactant on Lignite Surface

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1401
Author(s):  
Xuanlai Chen ◽  
Guochao Yan ◽  
Xianglin Yang ◽  
Guang Xu
Keyword(s):  
Hydrogen Bonds ◽  
Gemini Surfactants ◽  
Relative Concentration ◽  
Sodium Dodecyl ◽  
Large Angle ◽  
Molecular Chain ◽  
Dynamics Simulation ◽  
Practical Significance ◽  
Adsorption Characteristics ◽  
Binary Model

In order to explore the adsorption characteristics of sulfonate gemini surfactants on the surface of lignite, the molecular dynamics simulation method was used, and A kind of sulfonic acid bis sodium salt (S2) and the sodium dodecyl sulfate (SDS) were selected. A binary model of surfactant/lignite adsorption system and a ternary model of water/surfactant/lignite system were constructed, and a series of properties such as adsorption configuration, interaction energy, order parameters, relative concentration distribution, number of hydrogen bonds, etc., were analyzed. The results showed that the adsorption strength of S2 on the surface of lignite was higher than that of SDS. The results indicated that the large-angle molecular chain in S2 tended to become smaller, the small-angle molecular chain tended to become larger, and the angle between the molecular chains and the Z axis tended to be concentrated, making the formed network structure denser during the adsorption process. The number of hydrogen bonds in the water-coal system was 42, and the number of hydrogen bonds in the system after S2 adsorption was 15, which was much lower than the 23 hydrogen bonds in the system after SDS adsorption, and S2 could better adsorb and wrap the oxygen-containing groups on the surface of the lignite. The comparative study of the adsorption characteristics of the two surfactants on the surface of lignite can help us better understand the influence of the surfactant structure on the adsorption strength. The research results have important theoretical and practical significance for developing new surfactants, and enriching and developing the basic theory of coal wettability.

scholarly journals Molecular Docking, Dynamics Simulation, and Scanning Electron Microscopy (SEM) Examination of Clinically Isolated Mycobacterium tuberculosis by Ursolic Acid: A Pentacyclic Triterpenes

2019 ◽  
Vol 19 (2) ◽  
pp. 328
Author(s):  
Dian Ayu Eka Pitaloka ◽  
Sophi Damayanti ◽  
Aluicia Anita Artarini ◽  
Elin Yulinah Sukandar
Keyword(s):  
Electron Microscopy ◽  
Molecular Dynamics ◽  
Scanning Electron Microscopy ◽  
Cell Wall ◽  
Mycobacterium Tuberculosis ◽  
Ursolic Acid ◽  
Resistant Strain ◽  
Dynamics Simulation ◽  
Computational Docking ◽  
Scanning Electron

The purpose of this study was to analyze the inhibitory action of ursolic acid (UA) as an antitubercular agent by computational docking studies and molecular dynamics simulations. The effect of UA on the cell wall of Mycobacterium tuberculosis (MTB) was evaluated by using Scanning Electron Microscopy (SEM). UA was used as a ligand for molecular interaction and investigate its binding activities to a group of proteins involved in the growth of MTB and the biosynthesis of the cell wall. Computational docking analysis was performed by using autodock 4.2.6 based on scoring functions. UA binding was confirmed by 30 ns molecular dynamics simulation using gromacs 5.1.1. H37Rv sensitive strain and isoniazid-resistant strain were used in the SEM study. UA showed to have the optimum binding affinity to inhA (Two-trans-enoyl-ACP reductase enzyme involved in elongation of fatty acid) with the binding energy of -9.2 kcal/mol. The dynamic simulation showed that the UA-inhA complex relatively stable and found to establish hydrogen bond with Thr196 and Ile194. SEM analysis confirms that UA treatment in both sensitive strain and resistant strain affected the morphology cell wall of MTB. This result indicated that UA could be one of the potential ligands for the development of new antituberculosis drugs.

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