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Concentration effect
About: Concentration effect is a research topic. Over the lifetime, 3045 publications have been published within this topic receiving 108994 citations.
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TL;DR: In this paper, the effects of two of the most important processing parameters, spinning voltage and solution concentration, on the morphology of the fibers formed were evaluated systematically, and it was found that spinning voltage is strongly correlated with the formation of bead defects in the fibers, and that current measurements may be used to signal the onset of the processing voltage at which the bead defect density increases substantially.
2,684 citations
TL;DR: In this paper, the influence of different process parameters on the electric current and volume and surface charge density in the polymer jet was measured and the electric conductivity and permittivity were measured as well.
954 citations
TL;DR: In this article, the scaling picture of de Gennes et al. was extended to both unentangled and entangled regimes of intrinsically flexible polyelectrolyte solutions, and the dynamics of the chain is Rouse-like with viscosity weakly increasing with concentration η∼c 1/2 (Fuoss law), relaxation time decreasing with concentration τ Rouse ∼c -1/2, and diffusion coefficient independent of concentration.
Abstract: We extend and generalize the scaling picture of de Gennes et al. and Pfeuty to both unentangled and entangled regimes of intrinsically flexible polyelectrolyte solutions. In semidilute solution the electrostatic persistence length of a polyelectrolyte is assumed to be proportional to the Debye screening length. If the salt concentration is low, the unentangled semidilute concentration regime spans three to four decades in polymer concentration. In this regime the dynamics of the chain is Rouse-like with viscosity weakly increasing with concentration η∼c 1/2 (Fuoss law), relaxation time decreasing with concentration τ Rouse ∼c -1/2 , and diffusion coefficient independent of concentration. Polyelectrolytes should form entanglements at the same relative viscosity as neutral polymer solutions (η≅50η s ). In the entangled regime of salt-free polyelectrolytes we predict the viscosity η∼c 3/2 , relaxation time to be independent of concentration, and diffusion coefficient D self ∼c -1/2 . Our predictions are found to compare favorably with experiments
817 citations
TL;DR: In this article, the percolation threshold of nanotubes in poly(propylene) and poly(polystyrene) matrices was investigated and a small increase in elastic modulus and decrease in tensile strength at low nanotube loading was observed, but as the concentration was increased there was a progressive increase in both strength and stiffness.
Abstract: The dispersion of nanotubes in polymer matrices has been investigated as a means of deriving new and advanced engineering materials. These composite materials have been formed into fibers and thin films and their mechanical and electrical properties determined. The nanotube concentration at which conductivity was initiated (the percolation threshold) varied with host polymer. In poly(propylene), this was as low as 0.05 vol.-%, while higher concentrations were required for polystyrene and particularly for ABS. There was a small increase in elastic modulus and decrease in tensile strength at low nanotube loading, but as the concentration was increased there was a progressive increase in both strength and stiffness.
687 citations
TL;DR: The phase behavior of the triblock copolymers dissolved in water has been studied using SANS as discussed by the authors, and the structural properties have been studied as a function of polymer concentration and temperature.
Abstract: The phase behavior of the triblock copolymers dissolved in water has been studied using SANS. The structural properties have been studied as a function of polymer concentration and temperature. At low temperature (T ≤ 15°C) and low polymer concentrations the unimers are fully dissolved Gaussian chains with radius R g =17 A. Close to ambient temperature, the hydrophobic nature of PPO causes aggregation of the polymers into spherical micelles with core sizes of the order of 40-50 A, somewhat temperature dependent. The concentration of micelles increased roughly linearly with temperature, until either a saturation is reached,where all the polymers are part of a micelle, or the volume density of micelles is so high that they lock into a crystalline structure of hard spheres
669 citations