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41.
Summary Second drawing of monoaxially drawn PP and PET films perpendicular to the first drawing direction has been investigated. At low draw ratios structural systems having an angle of 45° with regard to the second draw direction are formed. By increasing the draw ratio the structures rotate into the new preferred direction. The results lead to the impression that the structural transformations do not turn out molecule by molecule, but domain by domain.
Zusammenfassung Die Zweitverstreckung monoaxial verstreckter PP- und PET-Folien senkrecht zur Erstverstreckrichtung wird untersucht. Bei kleinen Verstreckgraden bilden sich Struktursysteme unter 45° zur Zweitverstreckrichtung; bei weiterer Verdehnung drehen sich die Strukturen in die Vorzugsrichtung. Die Ergebnisse vermitteln den Eindruck, daß die Strukturänderung nicht Molekül für Molekül, sondern Bereich für Bereich abläuft.
With 10 figures and 2 tables 相似文献
42.
Summary The drawing behaviour of amorphous PET-films in the temperature interval between room temperature and 160 °C has been investigated in the present paper. Measurements of stress-strain behaviour, of birefringence, of density, of heat of fusion, of melting point, of glass temperature, of crystal structure and of superstructure prove that drawing temperature and drawing velocity posses a determining influence on forming morphology and technological properties. Within the temperature interval from 85 to 105 °C using low drawing velocities a drawing process of films without any molecular orientation is observed.
Zusammenfassung Das Verstreckverhalten von amorphen PET-Folien im Temperaturbereich von Raumtemperatur bis 160 °C wird in der vorliegenden Arbeit untersucht. Messungen des Spannungs-Dehnungs-Verhaltens, der Doppelbrechung, der Dichte, der Schmelzenthalpie, des Schmelzpunktes, der Einfriertemperatur und der Kristall- und Überstruktur zeigen, daß Verstrecktemperatur und Verstreckgeschwindigkeit einen entscheidenden Einfluß auf die entstehende Morphologie und die technologischen Eigenschaften besitzen. Im Temperaturbereich zwischen 85 und 105 °C beobachtet man bei kleinen Verstreckgeschwindigkeiten eine Verstreckung der Folien ohne molekulare Orientierung. nt]mis|With 13 figures and 1 table相似文献
43.
After discussing the feasibility and possible usefulness of a neutron interferometer, we describe an arrangement whereby Fresnel interferences have been obtained for neutrons with wavelengths of about 4.4 Å in a 10 meter flight path with a 0.01 mm entrance slit, using two glass prisms instead of the Fresnel biprism. A useful separation of the two coherent beams of 0.06 mm has been reached. Possible improvements of the method are discussed. 相似文献
44.
John W.Grove 《数学物理学报(B辑英文版)》2010,30(2):563-594
This article describes mathematical models for phase separated mixtures of materials that are in pressure and velocity equilibrium but not necessarily temperature equilibrium. General conditions for constitutive models for such mixtures that exhibit a single mixture sound speed are discussed and specific examples are described. 相似文献
45.
Lutz I Kloas W Springer TA Holden LR Wolf JC Krueger HO Hosmer AJ 《Analytical and bioanalytical chemistry》2008,390(8):2031-2048
Xenopus laevis has been introduced as a model to study effects of endocrine-active compounds (EAC) on development and sexual differentiation.
However, variable and inconsistent data have raised questions about the reliability of the test methods applied. The current
study was conducted in two laboratories to develop, refine, and standardize procedures and protocols. Larvae were exposed
in flow-through systems to 17β-estradiol (E2), at concentrations from 0.2 to 6.0 μg E2 L−1 in Experiment 1A, and 0.015 to 2.0 μg E2 L−1 in Experiment 1B. In both studies survival (92%, 99%) and percentage of animals that completed metamorphosis (97%, 99%) indicated
reproducible biological performance. Furthermore, minor variations in husbandry led to significant differences in snout-to-vent
length, weight, and gonad size. In Experiment 1A, almost complete feminization occurred in all E2 treatment groups whereas
a concentration response was observed in Experiment 1B resulting in an EC50 of 0.12 μg E2 L−1. The final verified protocol is suitable for determining effects of EAC on development and sexual differentiation in X. laevis. 相似文献
46.
47.
Mario Glanz Sebastian Dechert Herbert Schumann Dietmar Wolff Dietmar Wolff Jürgen Springer 《无机化学与普通化学杂志》2000,626(12):2467-2477
The Influence of the Coordination Sphere of Samarocenes on the Synthesis of Liquid Crystalline Polymethacrylates (C5Me5)2Sm(THF)2 ( 1 ) reacts with 1,3‐Diisopropyl‐4,5‐dimethylimidazoline‐2‐ylidene C3N2Me2iPr2 (iPr‐carben) with formation of (C5Me5)2Sm(iPr‐carben) ( 3 ). The reaction of (C5Me4Et)2Sm(THF)2 ( 2 ) with Al2Me6 in toluene yields [(C5Me4Et)2Sm(CH3)Al(CH3)3]2 ( 6 ). 3 and 6 were characterized by single crystal X‐ray structure analysis. Via living polymerization of mesogenic methacrylates with the organosamarium complexes 1 , 2 , 3 , (C5Me5)2Sm(C3H5) ( 4 ), (C5Me5)2Sm(CH3)(THF) ( 5 ), 6 , and (C5Me4Et)2SmCH(SiMe3)2 ( 7 ), liquid crystalline homo‐ and blockcopolymers were obtained with narrow molecular mass distribution indexes in high yield. Partial competitive mechanisms are observed dependend of the structure of the catalyst and the polarity of the solvents. 相似文献
48.
S. Koltzenburg D. Wolff J. Springer O. Nuyken 《Journal of polymer science. Part A, Polymer chemistry》1998,36(15):2669-2679
We report the synthesis and characterization of a series of liquid crystalline polymers substituted with the 4′-methoxybiphenyl-4-yloxy group. The spacer length is varied from 4–8 methylene units. The materials are characterized by polarized light microscopy, differential scanning calorimetry, and X-ray analysis. All homologues show highly ordered phases. Additionally, the butylene polymer shows a broad nematic mesophase. For the first time, the narrow nematic phase of the hexylene homologue could be confirmed experimentally. X-ray analysis of the polymers made exact assignments of the low temperature phases possible, thus giving access to the analysis of the arrangement of the mesogenes within the layers. The pentylene homologue shows a distinct deviation from the behavior of the other polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2669–2679, 1998 相似文献
49.
Z.-K. Xu M. Bhning J. Springer F. P. Glatz R. Mülhaupt 《Journal of Polymer Science.Polymer Physics》1997,35(12):1855-1868
Gas transport of helium, hydrogen, carbon dioxide, oxygen, argon, nitrogen, and methane in three soluble poly(phenylene sulfone imide)s based on 2,2-bis(3,4-decarboxyphenyl) hexafluoropropane dianhydride (6FDA) has been investigated. The effects of increasing length of well-defined oligo(phenylene sulfone) units on the gas permeabilities and diffusivities were determined and correlated with chain packing of the polymers. Activation energies of diffusion and permeation were calculated from temperature-dependent time-lag measurements. The influences of the central group in the diamine moiety of 6FDA-based polyimides on physical and gas transport properties are discussed. The incorporation of a long oligo(phenylene sulfone) segment in the polymer backbone decreases gas permeability and permselectivity simultaneously. The decreases in permeability coefficients can be mainly related to decreases in diffusion coefficients. Changing the central group of diamine moiety from S to SO2 leads to a 45–50% decrease in CO2 and O2 permeabilities without appreciable increase in the selectivities. This is considered to be due to the formation of charge transfer complexes. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1855–1868, 1997 相似文献
50.
Giancarlo Galli Emo Chiellini Oriano Francescangeli Dino Ferri Dietmar Wolff Jürgen Springer Michele Laus Annino S. Angeloni 《Macromolecular Symposia》1997,121(1):235-244
Liquid crystalline block copolymers are new materials in which multiple molecular interactions can provide the driving force for complex phase behaviors and states of order. Block copolymers containing both liquid crystalline main-chain polyester and side-group polymethacrylate blocks were investigated. They phase separated in the liquid crystalline state and their individual mesophases coexisted. The copolymers responded very differently when either a mechanical or a magnetic field was used for alignment. In the fibers the orientations of the side-group and main-chain smectic planes with respect to the fiber axis depended critically on the block lengths and on their distinct tendencies to align, whereas under a magnetic field the mesogens aligned collectively with their long molecular axis parallel to the field, independent of the copolymer structure. 相似文献