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Summary Diffusion coefficients and their temperature coefficients were obtained on a series of four polyurethanes believed to differ mainly in their molecular chain stiffness, and on one partially crystalline polyurethane of high molecular symmetry having flexible chains. The diffusion coefficients of CO2 in these materials and their temperature dependence are f ound to be much lower than those of many other typical organic polymers, notably rubbers. The data are interpreted in terms of theH-bonds formed between neighbouring polymer chains which are thought to make for regions of high packing efficiency, interrupted at irregular intervals by more open regions of small size. The effect of molecular chain flexibility appears to be smaller than the influence of theH-bonding.
Zusammenfassung Diffusionskoeffizienten und ihre Temperaturkoeffizienten wurden an einer Serie von 4 Polyurethanen erhalten, von denen anzunehmen ist, daß sie sich hauptsächlich in ihrer Kettensteifheit unterscheiden, und ferner an einem partiell kristallinen Polyurethan hoher molekularer Symmetrie mit flexiblen Ketten. Die Diffusionskoeffizienten von CO2 in diesen Materialien und ihre Temperaturabhängigkeit erwiesen sich als viel niedriger als die für viele andere typische organische Polymere, insbesondere für Gummis. Die Daten lassen sich aufgrund der H-Bindungen zwischen benachbarten Ketten deuten, durch die Bereiche höherer Packungsdichte, unterbrochen von irregulär geformten, mehr offenen Bereichen kleiner Ausdehnung, entstehen mögen. Die Effekte der Kettenbeweglichkeit scheinen kleiner als der Einfluß der Wasserstoff-Brückenbindung zu sein.相似文献
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M. Barth C. De Clercq E. A. De Wolf J. J. Dumont D. P. Johnson J. Lemonne P. Peeters R. Contri H. Drevermann L. Gerdyukov Y. Goldschmidt-Clermont G. Harigel C. Milstene J. P. Porte R. T. Ross P. Theocharopoulos C. Caso F. Fontanelli R. Monge S. Squarcia U. Trevisan J. F. Baland J. Beaufays J. Kesteman F. Grard P. A. van der Poel L. Gatignon W. Kittel W. J. Metzger D. J. Schotanus A. Stergiou R. T. van de Walle Y. Belokopitov P. V. Chliapnikov A. Fenuyk V. Kubic S. Lugovsky S. G. Nikitin V. Nikolaenko Y. Petrovikh V. Ronjin O. Tchikilev V. Yarba 《Zeitschrift fur Physik C Particles and Fields》1981,7(3):187-198
Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incidentK + beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π?'s and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π? cross section increases proportionally top LAB ?1/4 ; positive particles show almost no energy dependence atx=0. Particle ratios π+/π? are studied as a function ofx andy * and a comparison with 70 GeV/cK ? p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π± triggers at large |x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton. 相似文献
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D. Bertrand D. Johnson J. Lemonne P. Renton F. Van Den Bogaert J. Wickens A. Apostolakis R. Casali C. Caso A. Grant Y. Goldschmidt-Clermont G. Grammatikakis L. Pape J.P. Porte A. Stergiou B. Tallini G. Vassiliadis A. Lloret 《Nuclear Physics B》1977,128(3):365-396
Results are presented on the inclusive reactions at an incident antiproton momentum of 12 GeV/c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x, the rapidity, the transverse momentum of the V0 and the missing mass squared. The dependence of the Λ and polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/c are also made. Finally, events with two detected V0 are analyzed in order to study correlations arising from the production of two strange neutral particles. 相似文献
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M. Barth C. De Clercq E.A. De Wolf J.J. Dumont D.P. Johnson J. Lemonne P. Peeters H. Drevermann Y. Goldschmidt-Clermont G. Harigel C. Milstene J.R. Porte R.T. Ross M. Spyropoulou-Stassinaki S. Squarcia P. Theocharopoulos C. Caso V. Yarba 《Nuclear Physics B》1981,192(2):289-314
We present results on the jet-like properties of multiparticle systems produced in K+p interactions at 70 GeV/c. The data analysed in terms of several variables commonly used to study the jet structure of an event. An extensive comparison is made with jets found in electron-positron annihilations and in deep inelastic νN interactions at comparable energy. Many similarities are found between low-pT jets in this experiment and jets observed in leptonic interactions. Our data are very well reproduced by the Field-Feynman quark fragmentation parametrisation but equally well by a longitudinal phase space model, suggesting that these similarities do not prove or disprove the universal character of the jet fragmentation. 相似文献
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J. L. Bailly S. Banerjee W. Bartl C. Caso Y. Chiba A. Ferrando F. Fontanelli T. Gemesy R. Hamatsu J. Hanton J. Hrubec Y. Iga Yu. Ivanyshenkov L. Jenik N. Khalatyan E. Kistenev S. Kitamura J. M. Kohli S. Krasznovszky V. Kubik D. Kuhn B. B. Levchenko J. MacNaughton P. K. Malhotra J. C. Marin I. S. Mittra L. Montanet G. Neuhofer H. Oberguggenberger P. Porth R. Raghavan T. Rodrigo J. B. Singh S. Squarcia K. Takahashi L. A. Tikhonova U. Trevisan T. Yamagata V. Yarba G. Zholobov S. A. Zotkin EHS-RCBC Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,35(3):301-307
360 GeV/c proton interactions with aluminium (Al) and gold (Au) targets are studied using the European Hybrid Spectrometer (EHS) equipped with the Rapid Cycling Bubble Chamber (RCBC). Multiplicities, rapidity distributions and correlations between leading and other produced particles are presented and compared with Monte Carlo calculations based on the multi-chain and Lund models. 相似文献