نتایج جستجو برای: polymeric solutions
تعداد نتایج: 362040 فیلتر نتایج به سال:
This study was developed with the purpose to investigate the effect of polysaccharide/plasticiser concentration on the microstructure and molecular dynamics of polymeric film systems, using transmission electron microscope imaging (TEM) and nuclear magnetic resonance (NMR) techniques. Experiments were carried out in chitosan/glycerol films prepared with solutions of different composition. The f...
Performance of ultrafiltration membranes in ethanol–water solutions: effect of membrane conditioning
Several commercial polymeric ultrafiltration membranes were screened for their performance with aqueous ethanol solutions. The method of conditioning the membrane has a major effect on solvent flux, membrane integrity and their pressure ratings. Gradual solvent exchange with successively higher concentrations increased in small doses appears to work best with completely miscible solvents such a...
The self-assembly of CdS semiconductor nanocrystals (Q-CdS) as well-defined monolayer and multilayer films on glass, indium tin oxide, and gold surfaces was carried out. These were characterized by ultraviolet-visible spectroscopy, ellipsometry, and scanning tunneling microscopy. The adsorption of the polymeric anion hexametaphosphate (HMP) on the Q-CdS particle surface produced a negative surf...
We consider a mathematical model for polymeric liquids which requires the solution of high-dimensional Fokker-Planck equations related to stochastic differential equations. While Monte-Carlo (MC) methods are classically used to construct approximate solutions in this context, we consider an approach based on QuasiMonte-Carlo (QMC) approximations. Although QMC has proved to be superior to MC in ...
An optimal control problem for a mathematical model of a melt spinning process is considered. Newtonian and non–Newtonian models are used to describe the rheology of the polymeric material, the fiber is made of. The extrusion velocity of the polymer at the spinneret as well as the velocity and temperature of the quench air serve as control variables. A constrained optimization problem is derive...
Topological constraints, referred to as entanglements in the literature, dominate the viscoelastic behavior of high molecular weight polymeric liquids. To give a microscopic foundation of the phenomenological tube models which successfully describe this behavior, we have recently introduced a method for identifying the so-called primitive path mesh that characterizes the microscopic topological...
This paper represents a continuation of the series concerning experimental determination of vapour–liquid equilibria (VLE) in diluted polymer + solvent systems. In the previous papers we dealt with the polymeric flow improvers + toluene, hexane, chloroform1,2, poly(acrylic acid) + water3, poly(methyl methacrylate) + acetone3, and poly(methyl methacrylate) + 2-butanone4 systems. The aim of this ...
Soft lithographic techniques were used to fabricate polymeric microparticles for drug delivery applications. The microparticles were made of thermoplastics and thermosets from different types of precursors including reactive resin and polymer solutions in organic solvents or water. The microparticles produced using these methods were made of widely used polymers for drug delivery with highly un...
Constitutive models for the dynamics of polymer solutions traditionally rely on closure relations extra stress or related microstructural variables (e.g., conformation tensor) linking them to flow history. In this work, we study eigendynamics tensor within GENERIC framework in mesoscopic computer simulations separate effects nonaffine motion from other sources non-Newtonian behavior. We observe...
Nowadays, finely controlling the mechanical properties of polymeric materials is possible by incorporating supramolecular motifs into their architecture. In this context, the synthesis of a side-chain terpyridine-functionalized poly(2-(dimethylamino)ethyl methacrylate) is reported via reversible addition-fragmentation chain transfer polymerization. By addition of transition metal ions, concentr...
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