Henryk Wyciślik

Modifications of crystalline structure of peo polymer electrolytes with ceramic additives

Abstract Modifications of PEONaI polymer solid electrolytes by adding alumina powders were studied. Conductivity of prepared flexible films was improved at least one order of magnitude in comparison to pristine PEONaI electrolytes. The results were compared with those obtained previously by us for PEO based composite solid electrolytes containing NASICON.

PEO-based polymer blends as materials for solid electrolytes

Abstract Two different methods leading to the preparation of highly conductive polymer solid electrolytes are described. The polymers were modified by the addition of ceramic powders or organic polymers used as crystallization retarders. In both cases the room-temperature ionic conductivities were greatly improved. The reported values of ionic conductivity are higher than 10−5 S/cm at ambient temperatures, which is at least two orders of magnitude higher than for pristine PEO-based systems. The addition of ceramic particles causes an increase in the mechanical and temperature stability of the studied polymer electrolytes. All of the investigated samples are highly amorphous and their structures are stable over time.

Study of electrorheological properties of poly(p-phenylene) dispersions

Samples of powdered poly(p-phenylene) lightly doped with ferric chloride were dispersed in silicone oil and the observed electrorheological (ER) effect was studied. The conjugated polymers were obtained in three different synthetic procedures resulting in materials of different crystallinity, which was then additionally modified by annealing in vacuum. The polymer samples were carefully characterized and their electric conductivity and permittivity, doping level, x-ray diffractograms, Fourier-transform infrared spectra, and grain size distribution were determined. The influence of these properties on the magnitude of the ER phenomenon was examined. It was found that the ER activity of the suspensions depended strongly on the crystallinity of a dispersed polymer. This observation was correlated with the ionic conductivity of the material leading to the conclusion that the ER effect in suspensions of FeCl3 doped polyphenylene resulted from bulk polarization processes relying on movement of ions within the p...

Electrorheological properties of polyphenylene suspensions

Abstract Electrorheological (ER) fluids are currently being extensively investigated since their technical applications look very promising. The effect relies on rapid and reversible changes of viscosity of an ER fluid upon application of electric field. Doping of a conjugated polymer increases its electrical conductivity σ and dielectric constant e. Since factors determining values of these two parameters are different, it is sometimes possible to prepare a material of high e and low σ, which is the basic requirement for a main component of an ER fluid. Thus, conjugated polymers can be used in formulation of these fluids. Poly( p -phenylene) (PPP) treated with ferrous chloride was chosen and its bulk electrical properties were investigated by means of impedance spectroscopy. The values of e were 40–130 and the values of σ were 10 −8 -10 −6 S/cm. ER fluids were prepared from the polymer powder and silicone oil, and their ER properties were studied. The fluids exhibited Bingham-like behaviour. The magnitude of the ER effect increases with e but saturation at dielectric constants exceeding 100 is observed. This saturation seems to be a general feature of any ER fluid. Correlations between material parameters of the doped bulk PPP and the ER effect are shown.

Mixed conductivity in poly(p-phenylene) doped with iron chloride

Abstract Poly( p -phenylene) is a conjugated polymer that becomes conductive after doping. It has been demonstrated that the amorphous polymer lightly doped with iron(III) chloride exhibits both electronic and ionic conductivity in the range 10 −8 –10 −5 S/cm. Annealing the pristine amorphous polymer and doping it to the same level leads to a partially crystalline material, the exclusively electronic conductivity of which is one order of magnitude higher. The relative dielectric constant, however, seems to be unaffected by the polymer structure. The temperature dependencies of both components of the conductivity were measured giving similar values of activation energies within the range 0.29–0.36 eV.

Electrochemical studies of polypyrrole doped with ferrocyanide anions

Abstract Thin films of polypyrrole-ferrocyanide have been characterized using a rotating ring-disk electrode. It has been shown that the total amount of ferrocyanide is removed from the system in the first reduction-oxidation cycle if an appropriately low potential is applied during polypyrrole polymerization. If the polymerization potential reaches higher values than 0.6 V versus SCE in aqueous solutions, a significant irreversibility of the redox reaction results, leading in turn to the existence of non-removable anions in the polymer film. The linear relationship between the amount of released dopant registered at the ring and the film thickness indicates a homogeneous distribution of the dopant within the polypyrrole matrix.

Electrorheological effect in suspensions of conductive polymers

Abstract Electrorheological (ER) effect relies on increase of viscosity of a fluid under electric field. In the present study electrorheological fluids (ERFs) were prepared out of FeCl 3 doped poly( p -phenylene) and silicone oil. Rheological properties of the ERFs were measured under electric field up to 2.2 kV/mm. Influence of electric field and composition of the fluids on magnitude of the ER effect were studied. It was found that the ER effect is observed in ERFs containing amorphous polymer and not a semi-crystalline one. This has been attributed to ionic contribution of conductivity in the amorphous polymer which is not present in the crystalline material.

Electrorheological effect in suspensions of polyaniline

Abstract The electrorheological (ER) effect relies on the increase of viscosity of a fluid under electric field. The studied ER fluids (ERFs) were prepared out of silicone oil and polyaniline lightly protonated with four different acids of p K a values from −8 to +1.8. Rheological properties of the ERFs were measured under electric field up to 2.3 kV/mm. The influence of the protonation level of polyaniline and the acid used on the magnitude of the ER effect was studied. We propose an explanation of the observed relations based on measurements of dielectric properties of the polymers. The strongest ER effect was observed for polyaniline samples whose relaxation frequency was about 8 kHz, supporting the idea that the relatively slow polarisation processes were responsible for the ER effect. In addition, it was demonstrated that conductivity and dielectric constant of the polymers depended on the strength of the acids applied.

Photodiffusion kinetic studies by means of elemental analysis of Ag doped As2S3 glass

Abstract Photodiffusion has been observed in light irradiated As 2 S 3 /Ag two layer samples. X-ray fluorescence analysis has been utilized to determine the chemical composition of the photoreaction product giving the formula Ag 2.6 As 2 S 3 . The values of the photoreaction rate estimated from the analytical results satisfactorily agree with the analogous values derived from the electrical resistance measurements. The photodiffusion phenomenon models are also discussed.

Composite polymeric electrolytes based on poly(ethylene oxide) matrix and metallic aluminum filler

Abstract The mixed-phase composite electrolytes have been widely studied. The conductivity enhancement mechanism, which assumes amorphisation of the polymer matrix at the polymer-filler interface, is widely accepted. The contrary effect of the matrix stiffening and thus the decrease of conductivity was observed for a higher concentration of a wide range of inorganic fillers. Finally, the maximum conductivity is observed for 10–20 wt.% of the additive. In this work, a system containing small grains of metallic aluminum is investigated by the means of XRD, DSC, EIS, SEM and FT-IR. Contrary to previous studies, the present system shows maximum conductivity for a much smaller amount of added grains (1–2 wt.%). The highest ambient temperature conductivity value is higher than 5×10 −6 S cm −1 . The observed conductivity is of purely ionic character. The Almond–West Formalism was used to study the mechanism of conductivity in this system.