Kinetics of pyrolysis and properties of carbon black from a scrap tire

The pyrolysis of rubber from the sidewall and tread of a passenger car tire was carried out in a nitrogen flow at a wide range of final temperatures. Derivative thermogravimetric analysis (DTG) was applied to examine the kinetics at the different process conditions of completed pyrolysis. Two characteristic stages were observed in the DTG curves. The first stage corresponded to the decomposition of processing oil, plastifier, and additives, whereas the rubber polymer was decomposed in the second stage. Several properties of the carbon black formed by the pyrolysis such as ash content, specific surface area, and pore size distribution were determined. A change of the internal structure of the rubber particle in the meso-and macroregions of the pore size was observed. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Polymerization of styrene initiated by heterogeneous macromolecular initiator

High molecular weight monodisperse polystyrene has been prepared in an emulsion system by using powdered oxidized isotactic polypropylene as an initiator together with triethylenetetramine as an activator. Rate of polymerization increases linearly with emulsifier concentration and also with triethylenetetramine concentration to a certain extent. Molecular weight of polystyrene increases linearly with conversion and with emulsifier concentration, and decreases with triethylenetetramine concentration. For this polymer $\text{M}{}_{\mathrm{w}}\text{M}{}_{\mathrm{n}}$ is between 1·005 and 1·134. Fast initiation by active centres bonded on large solid surface, at the beginning of polymerization, and the existence of long living radicals were indicated by continuation of polymerization even after separation of the macromolecular initiator from the system in an inert atmosphere.     

Non-coherent scattering in subordinate lines: II. Collisional redistribution

A suitable form of the laboratory-frame redistribution function for the resonance scattering in subordinate lines, allowing for the radiative as well as collisional broadening of both atomic levels involved, is derived. Starting from the quantum-mechanical atomic-frame redistribution of Omont et al., we rewrite it in the form of a linear combination of two redistribution functions r_V and r_III, discussed in the preceding paper. This form, which is a direct generalization of that for resonance lines, permits both a simple physical interpretation and an effective numerical evaluation of the corresponding laboratory-frame redistribution. The case of spatial degeneracy is also discussed. Considerable attention is drawn to a discussion of the basic physical assumptions used, namely, the impact approximation and the Maxwellian velocity-distribution for the lower state atoms. It is shown that both of these assumptions are reasonably well satisfied for a variety of cases of astrophysical interest. Finally, in the Appendix we try to clarify the question of the normalization of the redistribution functions (with respect to inelastic collisions), as well as the question of practical equivalence between the astrophysical applications of the results of Omont et al. and those obtained by Yelnik and Voslamber.     

New proof of a characterization of geodetic graphs

In [3], the present author used a binary operation as a tool for characterizing geodetic graphs. In this paper a new proof of the main result of the paper cited above is presented. The new proof is shorter and simpler.     

Pathological behavior of renormalization-group maps at high fields and above the transition temeprature

We show that decimation transformations applied to high-q Potts models result in non-Gibbsian measures even for temperatures higher than the transition temperature. We also show that majority transformations applied to the Ising model in a very strong field at low temperatures produce non-Gibbsian measures. This shows that pathological behavior of renormalization-group transformations is even more widespread than previous examples already suggested.     

Mass,internal energy,and Cauchy's equations in frame-indifferent thermodynamics

Communicated by D. Owen     

Planning in physics

Following some introductory notes on science, a brief summary of the structure, contents and principal aims of the State Plan of Scientific Research currently being fulfilled in Czechoslovakia is given. More specifically, the different tasks and extent of work done under the State Plan in physics are described, the relative weight of this field compared to other regions of the plan is evaluated and certain long-term trends are mentioned. In the closing chapter an attempt is made to review the most interesting opinions on various aspects of contemporary physics research and its relations to society.     

Mixing ratio of the 0.34 MeV (M1 + E2) transition in49Ti

A direction-polarization correlation experiment was carried out in order to remove the ambiguity of the mixing ratio of the 0.34 MeV transition in⁴⁹Ti. The result of this experiment gives sufficient proof that the value is=+0.1.The authors wish to thank Mr. J. Holeek for his continuous help with the measurements and Ing. R. Michalec as well as other members of the Neutron Physics Department of our Institute for their interest and many helpful discussions.     

Painlevé classification of semilinear partial differential equations

The Painlevé-type classification of first degree second-order polynomial PDEs is performed.     

Beitrag zur spektrophotometrischen Aluminiumbestimmung mit Xylenolorange

Zusammenfassung Die Möglichkeit der Anwendung von Xylenolorange zur spektrophotometrischen Aluminiumbestimmung wurde nachgewiesen. Das optimale p_H wurde ermittelt, die Komplexbeständigkeit und der Einfluß von Begleitstoffen verfolgt. Ein Arbeitsverfahren zur Aluminiumbestimmung in Säuren, Laugen und Wässern wurde vorgeschlagen.

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Summary The feasibility of employing xylenol orange for the spectrophotometric determination of aluminium was established. The optimum p_H was determined, and the stability of the complex and the effect of accompanying materials were followed. A procedure was suggested for determining aluminium in acids, caustic solutions, and waters.

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Résumé On a étudié la possibilité d'appliquer l'Orangé Xylénol au dosage spectrophotométrique de l'aluminium. On a déterminé le p_H optimal et étudié la stabilité du complexe et l'influence des substances qui l'accompagnent. On propose un mode opératoire pour le dosage de l'aluminium dans les acides, dans les lessives alcalines et dans les eaux minérales.