Producing PVP Nanofibers by Electrospinning in N2

2012 ◽  
Vol 560-561 ◽  
pp. 701-708 ◽  
Author(s):  
Lu Li ◽  
Jie Xu ◽  
Tao Fang ◽  
Jin Geng ◽  
Detlef Freitag ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Phase Equilibrium ◽  
Phase Separation ◽  
Phase Behavior ◽  
Polymer Solution ◽  
Aspen Plus ◽  
Good Choice ◽  
The Other ◽  
Binary Phase ◽  
Novel Method

Electrospinning combined with nonsolvent-induced phase separation is a simple and novel method to produce porous nanofibers. In the study, Poly (vinylpyrrolidone) (PVP) nanofibers were fabricated using an electrospinning approach complemented by compressed nitrogen (N). N2 was used as the nonsolvent of choice. Besides, the tun2ning of N2 pressure and temperature can impact the nanofibers’ morphologies by altering phase behavior and mass transfer. Also, the other parameters affecting electrospinning of polymer solution were discussed. The results were demonstrated by extending the technique to PVP/dichloromethane (DCM) and PVP/ethanol (EtOH) systems. And the binary phase equilibrium of solvents (dichloromethane or ethanol) and N simulated by ASPEN PLUS 2006 demonstrates that N is not a 2good choice for producing hollow or po2rous polymer nanofibers.

Mass-transfer driven spinodal decomposition in a ternary polymer solution

Soft Matter ◽  
2019 ◽  
Vol 15 (23) ◽  
pp. 4614-4628 ◽  
Author(s):  
Douglas R. Tree ◽  
Lucas F. Dos Santos ◽  
Caden B. Wilson ◽  
Timothy R. Scott ◽  
Jan Ulric Garcia ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Phase Separation ◽  
Polymer Solution ◽  
Fluid Model ◽  
Combined Effects ◽  
Phase Separation Kinetics ◽  
Two Fluid Model ◽  
Ternary Polymer ◽  
Two Fluid ◽  
Separation Kinetics

A study of the combined effects of both mass transfer and phase separation kinetics on the widely used process of nonsolvent induced phase separation (NIPS) via a two-fluid model.

Modeling mass transfer and substrate utilization in the boundary layer of biofilm systems

1998 ◽  
Vol 37 (4-5) ◽  
pp. 139-147 ◽  
Author(s):  
Harald Horn ◽  
Dietmar C. Hempel
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Theory ◽  
Substrate Utilization ◽  
The Other ◽  
Concentration Profiles ◽  
Hydrodynamic Conditions ◽  
Time Axis ◽  
Transfer Coefficients

The use of microelectrodes in biofilm research allows a better understanding of intrinsic biofilm processes. Little is known about mass transfer and substrate utilization in the boundary layer of biofilm systems. One possible description of mass transfer can be obtained by mass transfer coefficients, both on the basis of the stagnant film theory or with the Sherwood number. This approach is rather formal and not quite correct when the heterogeneity of the biofilm surface structure is taken into account. It could be shown that substrate loading is a major factor in the description of the development of the density. On the other hand, the time axis is an important factor which has to be considered when concentration profiles in biofilm systems are discussed. Finally, hydrodynamic conditions become important for the development of the biofilm surface when the Reynolds number increases above the range of 3000-4000.

scholarly journals Pore-Scale Simulation of Confined Phase Behavior with Pore Size Distribution and Its Effects on Shale Oil Production

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1315
Author(s):  
Jingwei Huang ◽  
Hongsheng Wang
Keyword(s):  
Phase Equilibrium ◽  
Equation Of State ◽  
Pore Size Distribution ◽  
Phase Behavior ◽  
Pore Size ◽  
Size Distribution ◽  
Critical Role ◽  
Shale Oil ◽  
Pore Scale ◽  
Modified Equation

Confined phase behavior plays a critical role in predicting production from shale reservoirs. In this work, a pseudo-potential lattice Boltzmann method is applied to directly model the phase equilibrium of fluids in nanopores. First, vapor-liquid equilibrium is simulated by capturing the sudden jump on simulated adsorption isotherms in a capillary tube. In addition, effect of pore size distribution on phase equilibrium is evaluated by using a bundle of capillary tubes of various sizes. Simulated coexistence curves indicate that an effective pore size can be used to account for the effects of pore size distribution on confined phase behavior. With simulated coexistence curves from pore-scale simulation, a modified equation of state is built and applied to model the thermodynamic phase diagram of shale oil. Shifted critical properties and suppressed bubble points are observed when effects of confinement is considered. The compositional simulation shows that both predicted oil and gas production will be higher if the modified equation of state is implemented. Results are compared with those using methods of capillary pressure and critical shift.

Investigation on Polymer Adsorption and Retention in a Polymer Flooded Reservoir

2013 ◽  
Vol 734-737 ◽  
pp. 1200-1203
Author(s):  
Shu Qiang Liu ◽  
Ji Cheng Zhang ◽  
Jin Cheng Xu
Keyword(s):  
Polymer Solution ◽  
Influencing Factors ◽  
Polymer Adsorption ◽  
Solution Concentration ◽  
Injection Rate ◽  
The Other ◽  
Injection Time ◽  
Factors Affecting ◽  
Dynamic Factors ◽  
Polymer Retention

During polymer flooding, certain amount of polymer would be lost. Polymer retention causes sweep volume expanding on one side, it also causes polymer loss on the other. Therefore, it is a very important topic to study the influencing factors of polymer retention. There are many factors affecting polymer retention process. This paper mainly studied the influence from dynamic factors such as polymer solution concentration, injection rate, injection time, injected pv number. This paper investigated the influence of these factors on polymer retention process, and optimized these factors to minimize polymer loss in reservoir.

Solidification characteristics of polymer solution during polyvinylidene fluoride membrane preparation by nonsolvent-induced phase separation

2013 ◽  
Vol 438 ◽  
pp. 77-82 ◽  
Author(s):  
Toru Ishigami ◽  
Keisuke Nakatsuka ◽  
Yoshikage Ohmukai ◽  
Eiji Kamio ◽  
Tatsuo Maruyama ◽  
...  
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Polyvinylidene Fluoride ◽  
Membrane Preparation

scholarly journals A novel method of sintering hybrid steels in an improved semiclosed container system

2013 ◽  
Vol 45 (3) ◽  
pp. 379-383 ◽  
Author(s):  
A. Cias
Keyword(s):  
Mechanical Properties ◽  
Structural Steels ◽  
Laboratory Scale ◽  
The Other ◽  
Reduction Reactions ◽  
High Affinity ◽  
Conventional Sintering ◽  
Superior Mechanical Properties ◽  
Novel Method

Conventional sintering techniques for structural steels have been developed principally for Cu and Ni containing alloys. Applying these to Cr and Mn steels (successful products of traditional metallurgy) encounter the problem of the high affinity for oxygen of these elements. A solution is employing a microatmosphere in a semiclosed container which favours reduction reactions. This has already proved successful on a laboratory scale, especially with nitrogen as the furnace gas. Further modifications to the system, now described, include the use of two sintering boxes, one inside the other. Superior mechanical properties, even using air as the furnace gas, are attainable.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

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