Dope formulation

In the case of cellulose acetate (CA) casting dopes the solution structurization is mainly due to hydrogen bonding between polymer molecules and additives (swelling agents) in the solution. Therefore, a choice of a proper additive is an important step in the casting dope formulation. 

Finite size algorithms have been used extensively to study the edge states and systems with impurities, where substantial improvement of the accuracy is needed to characterize the various properties of a finite system. The DMRG method has been applied to diverse problems in magnetism study of spin chains with s > 1/2 [72], chains with dimerization and/or frustration [71, 73, 74], coupled spin chains [71, 75, 76], to list a few. The method has also been used to study models with itinerant fermions [77, 78], Kondo systems[79, 80, 81, 82], as well as coupled fermion chains [83, 84], including doping. Formulations for systems with a single impurity [85, 86] as well as randomly distributed impurities [87] and disorder [88] have also been reported. There has also been a study of the disordered bosonic Hubbard model in one dimension [89]. 

Over the past decade, many attempts have been reported to enhance separation performances of ultrafiltration (UF) and nanofiltration (NF) membranes through variation of different parameters involved during the membrane preparation process such as dope formulation, casting/spinning conditions, and posttreatment [1-5]. Of the parameters studied, it is found that the utilization of advanced materials in preparing membrane of improved properties stiU remains top priority among the community of membrane scientists worldwide. 

The dope formulation prepared from PPBES for support membrane fabrication was not disclosed. 

PAN-based carbon fiber and activated carbon fiber is not an easy task, since it involves many steps that must be carefully controlled and optimized. Such steps are the dope formulation, spinning and post spinning processes as well as the pyrolysis process. At the same time, there are several factors that need to be considered in order to ensure the success of each step. However, among all steps, the pyrolysis process is the most... 

The dope formulation for dense mixed-matrix films must be revisited for making asymmetric membranes as the structure of the membrane is controlled by phase separation kinetics. Different solvents used in dense film formulation may be used in asymmetric formulations to control the phase separation rate of the membrane within the nonsolvent (quench) bath and obtain membranes of varying porosities." Further, nonsolvents and additives can be added to fine tone the morphology of the membrane to control pore sizes and suppress the formation of large voids within the membrane. """ Asymmetric skinned membranes can also contain a second more volatile solvent that can evaporate and form a high solids concentration layer (skin) on the exposed surface... 

Despite the fact that there has been extensive study on the preparation and characterizations of flat-sheet PVDF membranes [16-20] fabricated by NIPS, limited studies have been devoted to the fabrication and characterization of PVDF hollow-fiber membranes [21-24]. It is well accepted that the phase inversion process of hollow-fiber membranes is much more complex than that of flat-sheet membranes, and the controlling factors for the former during membrane formation are distinctly different from those for the latter. One essential difference is the dope formulation that affects the dope viscosity. Usually, a polymer dope possessing a viscosity of... 

Characterization of polymer solutions used in membrane preparation can provide useful information on adjusting dope formulation. On the other hand, the characterization of membrane separation properties can be carried out by various techniques. Each pore size-determining technique has its advantages and limitations thus, one should select a suitable technique based on the requirements on applications. 

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