Über die Proliferationsfähigkeit hochvernetzter glasiger Polymerer

Zusammenfassung Die Modifizierung hochvernetzter Styrol—Divinylbenzolcopolymerisate durch Zusatz von Verdünnungsmitteln bei der Polymerisation führt zur Bildung proliferationsfähiger Polymerer. Es besteht ein enger optimaler Zusammensetzungsbereich. Der Zusammenhang der Proliferationsfähigkeit mit Gleichgewichtsquellung, permanenter Porosität und Gehalt an anhängenden Doppelbindungen wird untersucht; die Morphologie des Proliferationsprozesses wird in mikrokinematographischen Zeitrafferaufnahmen festgehalten.

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The modification of highly crosslinked styrene—divinylbenzene copolymers by adding diluents to the polymerizing system yields polymers showing proliferous polymerization. There exists an optimum concentration range of diluent. The correlation of proliferous polymerization to equilibrium swelling, permanent porosity, and content of pendent double bonds is investigated. The morphology of the proliferation process is observed in micro time lapse motion pictures.

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Mit 10 Abbildungen     

Residual entropy of the one-dimensional Ising antiferromagnet with general spin

We have calculated the ground-state degeneracy and the concominant residual entropy of the one-dimensional Ising antiferromagnet in a critical magnetic field. We demonstrate that the results obtained can be related to the ground-state properties of the q-state Potts antiferromagnet in the corresponding external field.     

The effect of carbon content on the beginning of slip in single crystals of Fe-3·2 wt%Si alloy

Specimens with 18 ppm and 100 ppm carbon of different orientations were deformed by compression (?～1·1×10^?4 s^?1) at the temperatures 150 °K, 195 °K, 293 °K, 393 °K and 483 °K. The measuredΨ(χ) andτ(χ) curves are presented. The changes of the curves caused by increased carbon content are discussed from the point of view of the low temperature induced cross-slip. Deviations from the Schmid law of critical resolved shear stress are found for both carbon contents. The dependence of the CRSS on temperature for specimens of standard purity has a slightly different course for orientationχ=?30° than for orientationsχ=0° andχ=+30°. These deviations are discussed in terms of the influence of normal stress on the slip. The course ofΔτ (difference between the CRSS in the MRSS plane for specimens with 100 ppm and 18 ppm of carbon) onχ is discussed using different models of lattice hardening due to interstitial impurities. These models can also be applied to the explanation of deviations ofτ(χ) curves from the Schmid law.     

Representations of an algebra of the Gell-Mann-Dashen type

LetG denote the infinitedimensional Lie algebra given by communtation relations [a _m ,a _n ] =c a _m+n (m, n=0, 1, ...), wherec are structure constants of the arbitrary centerless Lie algebra. The paper is devoted to the construction of a certain class of skewsymmetric irreducible representations (so called F-representations) of the algebraG .     

The syn and anti Steric Course in Bimolecular Olefin-Forming Eliminations

Earlier evidence led to the view that in bimolecular olefin-forming eliminations the anti steric course is generally preferred over the syn. Recent experiments, however, show that in some common bimolecular elimination reactions, notably those involving onium bases, syn- and anti-eliminations proceed side by side, the former preferentially leading to the trans- and the latter to the cis-olefins.