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The viscosity and speed of sound were measured in a poly(N‐isopropylacrylamide)–water system that exhibited a lower critical solution temperature. The measurements were performed in a polymer concentration range of 0.9–10 wt % and at temperatures ranging from 295 K to the demixing temperatures. The temperature dependence of the viscosity showed an unusual behavior in which three parts could be distinguished. Far from the demixing temperatures, the viscosity decreased with the temperature according to an Arrhenius relation. As the demixing points were approached, an intermediate region, weakly dependent on the temperature, was observed, and this was followed by a strong increase in the viscosity ending abruptly at a higher temperature. These breakdown points were identified with the demixing points and agreed very well with the cloud points determined by the optical method. The behavior of the viscosity close to the demixing points was believed to be determined by the strong critical effects. The concentration dependence showed an anomaly centered around 3%. Furthermore, the relative change of the viscosity with the temperature as a function of the concentration also showed an anomaly close to a concentration of 3%. The description of the critical behavior of the viscosity in terms of power laws gave a critical viscosity exponent equal to 0.056, which was much higher than what was theoretically expected. The use of a more general equation suggested a weak power divergence. The temperature dependencies of the speed of sound exhibited abrupt changes at temperatures corresponding to the phase transition. The agreement with optical cloud points and viscometric demixing points was very good. An exceptionally large isotope effect on the viscosity was observed, whereas that for the speed of sound was markedly lower and was in agreement with the expected value. These findings were qualitatively examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1219–1233, 2003

LiFePO4 is considered to be one of the most promising cathode materials for lithium ion batteries for electric vehicle (EV) application. However, there are still a number of unsolved issues regarding the influence of Li and Fe-site substitution on the physicochemical properties of LiFePO4. This is a review-type article, presenting results of our group, related to the possibility of the chemical modification of phosphoolivine by introduction of cation dopants in Li and Fe sublattices. Along with a synthetic review of previous papers, a large number of new results are included. The possibility of substitution of Li+ by Al3+, Zr4+, W6+ and its influence on the physicochemical properties of LiFePO4 was investigated by means of XRD, SEM/EDS, electrical conductivity and Seebeck coefficient measurements. The range of solid solution formation in Li1−3xAlxFePO4, Li1−4xZrxFePO4 and Li1−6xWxFePO4 materials was found to be very narrow. Transport properties of the synthesized materials were found to be rather weakly dependent on the chemical composition. The battery performance of selected olivines was tested by cyclic voltammetry (CV). In the case of LiFe1−yMyPO4 (M = Mn, Co and Ni), solid solution formation was observed over a large range of y (0 < y ≤ 1). An increase of electrical conductivity for the substitution level y = 0.25 was observed. Electrons of 3d metals other than iron do not contribute to the electrical properties of LiFe1−yMyPO4, and substitution level y > 0.25 leads to considerably lower values of σ. The activated character of electrical conductivity with a rather weak temperature dependence of the Seebeck coefficient suggests a small polaron-type conduction mechanism. The electrochemical properties of LiFe1−yMyPO4 strongly depend on the Fe substitution level.

Results on the kinetics of hydrogenation of a-pinene in high-pressure carbon dioxide, using Pt/C (1%) catalysts, are presented. Experiments were performed at different carbon dioxide pressures, so that the reaction mixture in contact with the solid catalyst would either be biphasic (liquid + gas) or a single supercritical phase. The technique involved the use of a high-pressure view cell, which allows direct visual observation of the number of phases in the reactor. The hydrogenations in biphasic conditions, at lower carbon dioxide pressures, are completed faster than in supercritical conditions. The results indicate that the pinene adsorption to the metal in the catalyst is the rate-controlling step.

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