Electrical Conductivity of Polymer Solution

Examination of the electrical conductivity of polymer solutions and choosing solvent mixture allowed the ([CH3 (CH2)3] N) - (TBAl) concentration in solution to be decreased from 5 down to 1 g/L due to adding the SI. The increase in PHB concentration up to 7 wt.% in a new solvent mixture was gained. 

The dynamic viscosity of polymer solutions of various compositions was measured as a fimction of PHB concentration with Heppler and Brookfield viscosimeters. The electrical conductivity of polymer solutions was calculated by the equation X = a/R, Ohm cm the electrical resistance was measured with E7-15 instrument. 

A comparison of the diameter of the electrospun fibers with the electrical conductivity of the solutions was shown in Figure 6. There was a significant drop in the diameter of the electrospun polymer fibers when the electrical conductivity of the solution increased. Beads were also observed due to low eonductivity of the solution, which results in insufficient elongation of a jet by eleetrieal foree to produce uniform fiber. 

It is well known that electrical conductivity of liquid solutions depends on the concentration of ions and their activity. The aqueous fluids in pipelines usually are electrolyte solutions and the conductivity is proportional to the salt concentration. The activity of the ions is related to temperature, and impurity like nonconductive chemical additives. Measurements of electrical conductivity could directly reflect the concentrations of chemicals such as salts, THIs (alcohol) and KHIs (polymers). (Clay and Medwin, 1977) [6] presented a simple correlation in which the sound velocity in sea water was described as a function of sahnity and temperature. Acoustic velocity has been successfully applied to investigate a variety of solutions and binary gas mixtures (Jerie, et al., 2004 Vibhu, et al., 2004 Goodenough, et al., 2005 Vyas, et al., 2006) [11] [25] [9] [26]. As a result, electrical conductivity and acoustic velocity were chosen as two parameters to simultaneously determine both salt and inhibitor concentrations. Artificial neural network (ANN) provides a numerical tool for such applications in which multi-parameter correlations are needed but the interaction and the relations between the parameters are not well known (Sundgren, et al., 1991 Broten and Wood, 1993) [21] [4]. Therefore, ANN correlations were developed to determine salt and inhibitor concentrations using the measured electrical conductivity, acoustic velocity, and temperature. 

Hydrogel Electrolyte, Fig. 2 Electrical conductivity of polymer hydrogel electrolyte and 6 mol L KOH aqueous solution at 25 °C... 

The reaction of benzene cations with polymer chains was indicated by an increase in the electrical conductivity of the solution relative to that of neat 02-saturated benzene (see Figure 1.14). The increase in conductivity was more pronounced the longer the polymer chain length - an effect that was attributed to the fact that the charges diffuse over the entire length of the chains and encounter chain ends within one period of the oscillating electric field. Consequently, the measured intrachain conductivity was seen to be frequency-dependent with a tendency to increase with increasing microwave frequency [104]. 

Figure 1.14 Electrical conductivity of benzene solutions containing the ladder-type polymer LPPP (3.15 X 10 base mol l average chain length 13, 16, 35, 54, from bottom to top).

This polymer may be prepared by stirring the molten w-aminoundecanoic acid at about 220°C. The reaction may be followed by measurements of the electrical conductivity of the melt and the intrinsic viscosity of solutions in w-cresol. During condensation 0.4-0.6% of a 12-membered ring lactam may be formed by intramolecular condensation but this is not normally removed since its presence has little effect on the properties of the polymer. 

Electrical Conductivity. The electrical conductivity of carbon blacks is inferior to that of graphite, and is dependent on the type of production process, as well as on the specific surface area and structure. Since the limiting factor in electrical conductivity is generally the transition resistance between neighboring particles, compression or concentration of pure or dispersed carbon black, respectively, plays an important role. Special grades of carbon black are used to donate to polymers antistatic or electrically conductive properties. Carbon blacks with a high conductivity and high adsorption capacity for electrolyte solutions are used in dry-cell batteries. 

Equipment based on the change in electrical conductivity of immobilized salt solution is available from American Instrument Company, Beckman Instruments, Nova Sina AG, and Ro-tronic AG. Equipment based on change in electrical capacitance of polymer thin films is available from WeatherMeasure and General Eastern Corporation. The approximate price range for water activity measurement instruments based on electronic sensors is 6000 to 8000. 

Figure 5. Electric conductivity as a function of polymer solution concentration [60],...

The potential applications for conducting polymers are enormous and this has stimulated a large amount of research into this area. Not surprisingly, solid-state NMR spectroscopy has been applied to study these amorphous, insoluble and in many cases crosslinked materials [24]. Looking at the CP/MAS spectra of a series conducing polyacenic polymers, some of which were doped with iodine, it was possible to see the effect of the halogen upon conductivity. These resins were prepared by a conventional procedure for the preparation a Novolak-type phenol-formaldehyde resin. After synthesis, the phenol-formaldehyde resin were dissolved and solutions were cast as a film and heat treated to between 590-670°C in a N2 atmosphere to form the polyacenic film. The electrical conductivity of the films was shown to increase... 

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