The change of the superstructure of semicrystalline polymers during deformation: results from small-angle scattering with synchrotron radiation

The change of the superstructure of different polyethylenes during uniaxial deformation is investigated. The method used is small-angle scattering with synchrotron radiation. For branched polyethylene (Lupolen 1840D) the whole deformation range is analyzed. Beginning with superstructure of the lamellar cluster type, the superstructure partly disappears on a time scale of a few minutes and the fibrillar structure is built up. The degree of destruction and rebuilding depends on the drawing temperature. For very high molecular weight polyethylene (GUR) a reversible change of the superstructure at higher deformation ratios and at different temperatures is observed. The superstructure of (ethylene—hexene) copolymers (TIPELIN) at high draw ratios depends on the drawing temperature and is almost independent of the side group content. Interfibrillar microcracks parallel to the draw direction are produced in samples with a low side group content for draw ratios λ ≥ 1.5.     

Numerical Analysis and Simulation Analysis for Space‐Time Data

Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio‐ temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg‐Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio‐temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space‐time data and theoretical simulation space‐time results was obtained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluation of the stability and analysis of halogenated furanones in disinfected drinking waters

A refined method for the sub-nanomolar analysis of 13 halogenated furanones in chlorinated drinking water is proposed which uses liquid-liquid extraction, methylation where necessary, gas chromatographic separation, and either micro-electron capture or ion trap mass spectrometric detection. Liquid-liquid extraction with methyl tert-butyl ether was demonstrated to be effective for recovery of halogenated furanones. Confirmation of the halogenated furanones identity and reduction of natural organic matter interference were achieved by ion trap tandem mass spectrometry. Compound stabilities and procedural efficiencies were evaluated to permit optimization of the method for reasonable sample volumes and a 1000:1 pre-concentration factor that would permit feasible sample collection in the field. Both chlorinated and brominated analogues of MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) were included in a suite of compounds targeted in a national occurrence study of disinfection by-products.     

Untersuchung der Temperaturabhängigkeit derg ik -Tensoren von Polyäthyleneinkristallen

Zusammenfassung Es wurden die Kristallitgröße und die Änderungen der parakristallinen Gitterstörungen aus den Linienbreiten des Röntgenweitwinkeldiagramms von lösungskristallisiertem linearem Polyäthylen bei den Temperaturen 15°K, 73°K, 173°K und Zimmertemperatur bestimmt. Es wurde eine Zunahme der Gitterstörungen mit fallender Temperatur gefunden.

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Summary The crystallite size and the paracrystalline distortions in polyethylene single crystals were evaluated by the measurement of the linewidth in the X-ray wide angle diagram at four different temperatures (15°K, 73°K, 173°K and 297°K). An increase of the lattice distortions with decreasing temperature was found.

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Vorgetragen auf der Arbeitssitzung des Fachausschusses Physik der Hochpolymeren in der Frühjahrstagung 1970 des Regionalverbandes Hessen-Mittelrhein-Saar der Deutschen Physikalischen Gesellschaft in Darmstadt, 10.–13. März 1970.     

Liquid chromatographic isolation of vincristine and vinblastine

A fundamentally new method is described for the separation of the dimeric indole alkaloids vincristine and vinblastine from monomeric indole alkaloid impurities. This method uses an RP-18 high-performance liquid chromatography column with a methanol-water mobile phase containing an inorganic acid and an unusually low concentration of inorganic buffer. By keeping the buffer concentration low, the elution of all indole alkaloids is retarded, but the dimeric ones are retarded more than the monomeric ones. A theoretical model developed to explain this behavior postulates that the anions of the buffer solubilize the protonated indole alkaloids by pairing with them. Lowering the buffer concentration reduces the availability of pairing ions and thus decreases the mobile phase affinity of protonated alkaloids, particularly those having a 2+ charge. A similar approach may be applicable in other situations where ionogenic organic compounds having a particular valence must be separated from related compounds having different valences, or from non-ionogenic compounds.     

A volumetric determination of arsenic and antimony in mixed manganese arsenide,antimonide and phosphide compounds

A procedure is described for the titrimetric determination, of arsenic and antimony without separation. Total combined arsenic and antimony were determined by reduction with tin(II) chloride and titration with permanganate; antimony is found by selective reduction with mercury(I) chloride and titration with permanganate. A precision of 0.1–0.2% was obtained for total combined arsenic and antimony, and approximately 1% for antimony alone (small amounts in the presence of large amounts of arsenic). The procedure was developed for and applied to the analysis of synthesized compounds of the type MnAs_1-xP_x and MnAs_1-ySb_y.