The Structure of Polychloroprene

1942 ◽  
Vol 15 (4) ◽  
pp. 847-853
Author(s):  
C. J. Birkett Clews
Keyword(s):  
Physical Properties ◽  
Crystalline Structure ◽  
Spatial Configuration ◽  
Unit Cell ◽  
Cross Linking ◽  
X Ray ◽  
Ray Density ◽  
Pass Through ◽  
Ray Methods ◽  
Identity Period

Abstract Specimens of polychloroprene and light-treated polychloroprene have been examined by x-ray methods. There is evidently no change in the crystalline structure of the two substances, although there are differences in physical properties which are ascribed to cross-linking of the long polychloroprene chains. This conclusion is confirmed by the x-ray work. The unit cell of polychloroprene is probably orthorhombic, with dimensions a=8.90 A.U., b=4.70 A.U., c=12.21 A.U. From the experimentally determined density of 1.086 g. per cc, it is deduced that there are four chloroprene units in the cell. The x-ray density (for the stretched material) is 1.14 g. per cc. The long chains lie parallel to the b-axis (the direction of stretching), and four of these chains pass through the unit cell. It is concluded, from the identity period, that the chain is not planar and a possible spatial configuration is given.

scholarly journals The structure of polychloroprene

1942 ◽  
Vol 180 (980) ◽  
pp. 100-107 ◽  
Keyword(s):  
Physical Properties ◽  
Crystalline Structure ◽  
Light Treatment ◽  
Unit Cell ◽  
Cross Linking ◽  
Chain Molecules ◽  
X Ray ◽  
Before And After ◽  
Ray Methods ◽  
Long Chain

Specimens of polychloroprene before and after light treatment have been examined by X -ray methods. There is no change in the crystalline structure, although there are differences in the physical properties ascribed to cross-linking of the long-chain molecules. The unit cell is possibly ortho­rhombic: a = 8·90 A , b = 4·70 A, c = 12·21 A, and contains four chloroprene (C 4 H 5 Cl) units.

Highly Polymeric Compounds. CLXIV. Unit Cell Diagrams and the Microstructure of “Single Crystals” of Rubber. Determination of the Lattice of Macromolecules of Rubber according to New X-Ray Methods

1939 ◽  
Vol 12 (4) ◽  
pp. 719-733
Author(s):  
Erwin Sauter
Keyword(s):  
Considerable Extent ◽  
Unit Cell ◽  
Fiber Axis ◽  
X Ray ◽  
Ordinary Temperature ◽  
Polymeric Compounds ◽  
Face Centered ◽  
Pass Through ◽  
Ray Methods

Abstract 1. The macromolecular lattice of rubber is rhombic and has the constants: a .......................12.60 ± 0.05 A.U. c ....................... 8.91 ± 0.05 A.U. b ....................... 8.20 ± 0.05 A.U. 2. The number of isoprene residues in the cell is computed to be 7.92, i.e., essentially 8; the density obtained roentgenographically is 0.974, which is in reasonable agreement with the value of 0.965 found experimentally. The discrepancies of earlier measurements are at the same time eliminated. (3) The four chains which pass through the unit cell in the direction of the fiber axis are probably columnar tub-like chains with a cis-arrangement at the double bonds which are assembled after the manner of a lattice face-centered on one side. (4) After being stretched to a considerable extent at ordinary temperature, eucolloidal “fused” rubber crystallizes with formation of microscopic crystalline regions of indefinitely great linear tension.

X-ray powder diffraction study of ZnGa2Te4

2002 ◽  
Vol 17 (1) ◽  
pp. 41-43 ◽  
Author(s):  
Rashmi ◽  
U. Dhawan
Keyword(s):  
Diffraction Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Tetrahedral Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Ray Density

ZnGa2Te4 was found to crystallize in a defect tetrahedral structure with possible space group I4(82) with Z=2. Complete X-ray powder diffraction data were obtained and the unit cell parameters a and c and X-ray density were calculated. These were a=0.5930(1) nm, c=1.1859(3) nm, and Dx=5.7×103 kg/m3.

Über die Kristallstruktur von KSc2 F7 / The Crystal Structure of KSc2 F7

1985 ◽  
Vol 40 (6) ◽  
pp. 726-729 ◽  
Author(s):  
Klaus Güde ◽  
Christoph Hebecker
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Unit Cell ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Unit Cell ◽  
R Value ◽  
Ray Methods

Abstract Single crystals of KSc2F7 have been prepared from a mixture of KF and ScF3 . The samples were investigated by X-ray methods. KSc2F7 crystallizes orthorhombically with a = 10.643(2), b = 6.540(1), c = 4.030(1) Å. These data indicate a close crystallographic connection to the monoclinic unit cell of KIn2F7 [1], But in contrast to KIn2F7 , KSc2 F7 crystallizes in space group No. 65. Cmmm - D192h. The R-value for 341 observed independent reflections is 0.060.

scholarly journals X-ray studies of the structure of hair, wool, and related fibres.- I. General

1931 ◽  
Vol 230 (681-693) ◽  
pp. 75-101 ◽  
Keyword(s):  
Physical Properties ◽  
Crystalline Structure ◽  
Human Hair ◽  
X Rays ◽  
Present Communication ◽  
Cellulose Fibres ◽  
X Ray ◽  
Usual Manner ◽  
Wide Range ◽  
Muscle Nerve

It is now some ten years since it was first realised that, in common with natural and artificial cellulose fibres, animal fibres with a protein basis are in many cases sufficiently crystalline to yield a pronounced interference figure when examined with monochromatic X-rays. Such “ X-ray fibre diagrams ” were reported in 1921 by HERZOG and JANCKE* for muscle, nerve, sinew, and hair, and in 1924 similar photographs from human hair were obtained by one of the present writers. From an X-ray examination of wool it was concluded by THREADGOLD that “ there is no evidence for assuming the wool fibres and yarns examined to have a crystalline structure,” but in 1927 EWLES and SPEAKMAN had already obtained wool interference figures precisely similar to those previously obtained from hair. The two last-named authors endeavoured to interpret their results in the light of certain physical properties, but it has since become clear that the problem of hair structure is sufficiently complex to necessitate an X-ray study of a wide range of materials under as great a variety of conditions as possible. The present communication is an account of the preliminary results of such an investigation. Over a hundred X-ray photographs have been taken, using copper K-radiation filtered of the MATHS FORMULA line by nickel foil about 1/100 mm. thick. The “ slit” was a rectangular aperture, 4 cm. x 0.5mm., the scattered rays from which were screened off in the usual manner by a secondary slit.

The Lattice of Rubber

1940 ◽  
Vol 13 (3) ◽  
pp. 547-548
Author(s):  
Lore C. Misch ◽  
A. J. A. Van Der Wyk
Keyword(s):  
Unit Cell ◽  
X Ray ◽  
Unit Cells ◽  
Ray Density ◽  
The Subject

Abstract The lattice of rubber has already been the subject of a number of investigations. All the unit cells suggested in these papers give an x-ray density which is far higher than the measured one (8–10 per cent). Furthermore, in all Weissenberg pictures published, it is striking that the equator reflection A2 is much longer than A1 and A3. We believe therefore that A2 is not a single reflection and that the angle between A1 and A2 is not 90° or nearly 90°. While we investigated this question experimentally, Morss published a paper, also assuming that A2 is a double reflection and making the assumption of double orientation. He calculated the unit cell for a number of angles and found an agreement with the observations at the angle of 70.5°. The cell contains 8 chains.

X-ray powder diffraction study of CuInSeTe

2000 ◽  
Vol 15 (1) ◽  
pp. 65-68 ◽  
Author(s):  
Rashmi ◽  
D. K. Suri
Keyword(s):  
Diffraction Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Chalcopyrite Structure ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Ray Density

CuInSeTe was synthesized by the melt and anneal technique. The compound crystallized in the chalcopyrite structure having space group I4¯2d with Z=4. Complete X-ray powder diffraction data were obtained and the unit cell parameters a and c, X-ray density and u parameter were calculated. These are a=0.5987(1) nm, c=1.1979(4) nm, Dx=5.96×103kg/m3, and u=0.2498. Atomic positions in the unit cell are proposed.© 2000 International Centre for Diffraction Data.

The construction and use of an X-ray goniometer. Crystal-structure of glyoxaline compounds (With Plate I.)

1926 ◽  
Vol 21 (112) ◽  
pp. 1-9 ◽  
Author(s):  
Gilbert Greenwood
Keyword(s):  
Crystal Structure ◽  
Unit Cell ◽  
X Ray ◽  
Derivatives Of ◽  
Ray Methods

In ordinary circumstances crystal-angles are measured by means of light reflected from the crystal-faces. In the partial or complete absence of faces the determination of axial ratios and angles may be impossible. In a recent investigation of certain derivatives of glyoxaline, an example of this was found. It was, in fact, the substance glyoxaline itself, which always occurred as long prisms having four faces in the prism-zone; the ends of the prisms were jagged and rough, and no siglls of optically reflecting-planes could be found on these ends. In such a case, X-ray methods of investigation are now available, and the problem in question is the determination of the dimensions of the unit-cell, not the complete X-ray inveatigation of the structure.

Strained heterocyclic systems. 12. The crystal structure of 1,8-diazabiphenylene

1984 ◽  
Vol 62 (11) ◽  
pp. 2235-2237 ◽  
Author(s):  
Betty R. Deroski ◽  
John S. Ricci Jr ◽  
J. A. Hugh MacBride ◽  
J. Hodge Markgraf
Keyword(s):  
Crystal Structure ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Aromatic Rings ◽  
Space Group ◽  
X Ray ◽  
Planar Molecule ◽  
Ray Methods

The structure of 1,8-diazabiphenylene (5) has been determined by X-ray methods. Crystals of 5 are monoclinic, space group P21/n, with a = 3.786(2), b = 8.532(1), c = 11.218 (2) Å, β = 92.24(2)°, and two molecules per unit cell. The planar molecule contains distorted aromatic rings with the smallest angle (112.9°) adjacent to the fused strained ring.

Radical Cation Salts of an Unsymmetrical BEDT-TTF Derivative: Molecular Structure and Physical Properties of (DIMET*)2CIO4 X THF

1985 ◽  
Vol 40 (12) ◽  
pp. 1703-1710 ◽  
Author(s):  
R. Heid ◽  
H. Endres ◽  
H. J. Keller
Keyword(s):  
Molecular Structure ◽  
Electrical Conductivity ◽  
Physical Properties ◽  
Crystal And Molecular Structure ◽  
Average Charge ◽  
Two Dimensional ◽  
X Ray ◽  
Radical Cation Salts ◽  
Solvent Molecules ◽  
Ray Methods

Abstract 4.5-Dimethyl-4'.5'-ethylenedithiolotetrathiafulvalene (DIMET) was obtained by reacting 4.5- ethylenedithiolo-1.3-dithioliumtetrafluoroborate with 4.5-dimethyl- 1.3-dithiolium-tetrafluoroborate in the presence of diisopropylethylamine or triethylamine. Electrocrystallization of this donor in different solvents like dichloromethane or tetrahydrofurane (THF) and with varying supporting electrolytes, like tetrabutylammonium hexafluorophosphate, triiodide, nitrate, perrhenate or perchlorate, results in a large number of well crystallizing compounds. The crystal and molecular structure of one of the isolated solids was elucidated by X-ray methods. (C10)H10S6)2CIO4 x C4H8O, Mr = 816.66, is triclinic, P1̄ , a = 6.731(5), b - 7.632(3), c = 33.32(3) Å , α = 96.53(5), β = 92.99(6), γ = 103.13(5)°, V - 1650.7 Å3, Z = 2, dc = 1.64 gem-3, final Rw = 0.077 for 1844 observed independent reflections. Sheets of cations with an average charge of 1/2+ are separated by sheets of anions and THF solvent molecules. Intermolecular S···S contacts result in two-dimensional physical properties. Electrical conductivity and thermopower measurements indicate two broad phase transitions at around 200 K and 80 K

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