Structure of Rubber

1939 ◽  
Vol 12 (2) ◽  
pp. 119-123
Author(s):  
C. J. B. Clews
Keyword(s):  
Solid State ◽  
Recent Work ◽  
Elastic Properties ◽  
Random Distribution ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Accurate Data ◽  
X Ray

Abstract The results of the x-ray study of rubber structure may be summarized as follow : (1) The unit cell is monoclinic, space group C2h5, a=8.53±0.05, b=8.16±0.05, c=12.66±0.05 A˚, β=83°20′, with four isoprene chains in the cis modification passing through the cell, which contains 8 C5H8 residues. (2) In the unstretched state there is a random distribution of ordered crystalline regions and disordered regions. On stretching, the crystalline regions become orientated in one or more crystallographic directions, thereby giving rise to the x-ray fibre diagram. The crystalline regions may be identified with the micelles, which are groups of Hauptvalenzketten bound together by van der Waals' forces; a given Hauptvalenzkette is undoubtedly associated with more than one micelle. It is possible that the abnormal elastic properties are due to the chains becoming aligned parallel to the direction of stretching, and in addition there may be some extension of the chains themselves. Such an effect has been observed by Astbury in his work on keratin. Some recent work on the structure of butadiene and its derivatives in the solid state is described, which, although offering no immediate solution of our problem, may prove of value when further accurate data are available, both for these compounds and for the corresponding rubbers.

Notizen: Solid State Structure of N,N-Dibenzylhydroxylamine

1995 ◽  
Vol 50 (4) ◽  
pp. 699-701 ◽  
Author(s):  
Norbert W. Mitzel ◽  
Jürgen Riede ◽  
Klaus Angermaier ◽  
Hubert Schmidbaur
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
State Structure ◽  
X Ray Diffraction ◽  
Space Group ◽  
Solid State Structure ◽  
X Ray

The solid-state structure of N,N-dibenzylhydroxylamine (1) has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P 21/n with four formula units in the unit cell. N,N-dibenzylhydroxylamine dimerizes to give N2O2H2 sixmembered rings as a result of the formation of two hydrogen bonds O - H ··· N in the solid state.

The Crystal Structure of Bis(2,2′:6′,2″-terpyridine)nickel(II) Perchlorate Hydrate

1995 ◽  
Vol 48 (7) ◽  
pp. 1373 ◽  
Author(s):  
AT Baker ◽  
DC Craig ◽  
AD Rae
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
Least Squares ◽  
Axial Compression ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Octahedral Symmetry ◽  
Space Group ◽  
X Ray

The crystal structure of bis (2,2′:6′,2″-terpyridine)nickel(II) bis (perchlorate) hydrate has been determined by single-crystal X-ray diffractometry . The compound is monoclinic, space group P21, with two molecules in a unit cell of dimensions a 8.827(4), b 8.910(2), c 20.148(9) Ǻ, β 98.71(2)°. The structure was refined by least-squares to a residual of 0.065 for 2184 observed reflections. The compound is found to be isomorphic with the iron(II) analogue previously reported: the cation has approximate D2d symmetry, with the main distortion from octahedral symmetry being an axial compression. Both the solid state reflectance and solution spectra have been measured and some significant differences are noted.

Synthesis and Crystal Structure of 5,10,15,20-Tetrakis(3,5-dinitrophenyl)porphyrin

1998 ◽  
Vol 02 (05) ◽  
pp. 391-396 ◽  
Author(s):  
P. BHYRAPPA ◽  
K. S. SUSLICK
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Structure Data ◽  
Crystal Structure Data ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
State Structure ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray

The synthesis, characterization and crystal structure of the octanitro-substituted porphyrin 5,10,15,20-tetrakis(3,5-dinitrophenyl)porphyrin, H 2 T (3,5- DNP ) P , are described. The solid state structure has two porphyrins in the unit cell with eight pyridine solvates and is made up from columnar arrays of the porphyrins. X-ray crystal structure data: monoclinic, space group P1 21/n1, a = 14.9996(9) Å, b = 8.2489(5) Å, c = 24.818(2) Å, α = 90 °, β = 104.172(1) °, γ = 90 °, V = 2977.3(3) Å3, dcalc = 1.440 g m-3, Z = 2.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

X-ray Structure Refinement and Vibrational Spectroscopy of Ca8Gd2 (PO4)6 O2

2013 ◽  
Vol 12 (10) ◽  
pp. 719-726
Author(s):  
R. Ayadi ◽  
Mohamed Boujelbene ◽  
T. Mhiri
Keyword(s):  
Solid State ◽  
General Formula ◽  
Vibrational Spectroscopy ◽  
Powder Diffraction ◽  
Infrared Spectra ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Unit Cell ◽  
Cell Group ◽  
X Ray

The present paper is interested in the study of compounds from the apatite family with the general formula Ca10 (PO4)6A2. It particularly brings to light the exploitation of the distinctive stereochemistries of two Ca positions in apatite. In fact, Gd-Bearing oxyapatiteCa8 Gd2 (PO4)6O2 has been synthesized by solid state reaction and characterized by X-ray powder diffraction. The site occupancies of substituents is0.3333 in Gd and 0.3333 for Ca in the Ca(1) position and 0. 5 for Gd in the Ca (2) position.  Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit-cell group analyses.

Fabrication and study the effect of the laser on the properties of the compound Tl2-xHgxBa2-ySryCa2Cu3O10+δ superconductor

2018 ◽  
pp. 168
Author(s):  
A. Kareem Dahash Ali ◽  
Nihad Ali Shafeek
Keyword(s):  
Transition Temperature ◽  
Solid State ◽  
Hydrostatic Pressure ◽  
Electrical Properties ◽  
Co2 Laser ◽  
Temperature Shift ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electrical Properties

This study included the fabrication of    compound (Tl2-xHgxBa2-ySryCa2Cu3O10+δ) in a manner solid state and under hydrostatic pressure ( 8 ton/cm2) and temperature annealing(850°C), and determine the effect of the laser on the structural and electrical properties elements in the compound, and various concentrations of x where (x= 0.1,0.2,0.3 ). Observed by testing the XRD The best ratio of compensation for x is 0.2 as the value of a = b = 5.3899 (A °), c = 36.21 (A °) show that the installation of four-wheel-based type and that the best temperature shift is TC= 142 K  .When you shine a CO2 laser on the models in order to recognize the effect of the laser on these models showed the study of X-ray diffraction of these samples when preparing models with different concentrations of the values ​​of x, the best ratio of compensation is 0.2 which showed an increase in the values ​​of the dimensions of the unit cell a=b = 5.3929 (A °), c = 36.238 (A°). And the best transition temperature after shedding laser is TC=144 K. 

Pb-Sb zrudnění z Antimonitové žíly, důl Rudolf, Bohutín (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 275-280
Author(s):  
Pavel Škácha ◽  
Jiří Sejkora
Keyword(s):  
Czech Republic ◽  
Chemical Composition ◽  
Empirical Formula ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Ore District ◽  
Archive Material

The Pb-Sb mineralization with dominant stibnite and plagionite and associated semseyite and zinkenite was found in an archive material collected at the Antimonitová vein, Bohutín, Březové Hory ore district (Czech Republic). Plagionite forms subhedral aggregates up to 1 mm in size. The unit-cell parameters of plagionite for monoclinic space group C2/c refined from the X-ray powder data are: a 13.4890(17), b 11.8670(14), c 19.997(2) Å, β 107.199(8)° and V 3057.9(6) Å3. Its chemical composition (average of 26 analyses, based on 30 apfu) corresponds to the empirical formula Pb5.02Sb8.15S16.82. Associated zinkenite is forming subhedral crystals up to 1 mm in size. Its empirical formula can be expressed as (Cu0.25Ag0.02Fe0.01)Σ0.28Pb9.22Sb22.19S41.31 (average of 26 analyses, based on 73 apfu). Semseyite aggregates have the empirical formula (Pb8.72Fe0.14)8.86Sb8.42S20.73 (average of 11 analyses, based on 38 apfu).

29Si NMR and XPS Investigation of the Structure of Silicon Oxycarbide Glasses Derived from Polysiloxane Precursors

1994 ◽  
Vol 346 ◽  
Author(s):  
R.J.P. Corriu ◽  
D. Leclercq ◽  
P.H. Mutin ◽  
A. Vioux
Keyword(s):  
Solid State ◽  
Photoelectron Spectroscopy ◽  
Solid State Nmr ◽  
Random Distribution ◽  
Silicon Oxycarbide ◽  
29Si Nmr ◽  
Xps Spectra ◽  
Excess Carbon ◽  
X Ray ◽  
Silicon Oxycarbide Glasses

ABSTRACTTwo silicon oxycarbide glasses with different compositions (O/Si ratio 1.2 and 1.8) were prepared by pyrolysis at moderate temperature (900 °C) of polysiloxane precursors. Their structure was investigated using quantitative 29Si solid-state NMR and X-ray photoelectron spectroscopy (XPS). The environment of the silicon atoms in the oxycarbide phase corresponded to a purely random distribution of Si-O and Si-C bonds depending on the O/Si ratio of the glass only and not on the structure of the precursors. At the light of the NMR results, the Si2p XPS spectra of the glasses may be interpreted using the contribution of the five possible SiOxC4-x tetrahedra. The Cls spectra of these glasses indicated the presence of oxycarbide carbon in CSi4 tetrahedra, similar to carbide carbon, and graphitic-like excess carbon.

Formation of a Cyclic Dimer Containing Two Mirror Image Monomers in the Solid State Controlled by van der Waals Forces

2011 ◽  
Vol 13 (18) ◽  
pp. 4818-4821 ◽  
Author(s):  
Zibin Zhang ◽  
Guocan Yu ◽  
Chengyou Han ◽  
Jiyong Liu ◽  
Xia Ding ◽  
...  
Keyword(s):  
Solid State ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Mirror Image ◽  
Cyclic Dimer
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