scholarly journals The crystalline structure and properties of tartaric acid

1923 ◽  
Vol 102 (718) ◽  
pp. 506-528 ◽  
Keyword(s):  
Tartaric Acid ◽  
Crystalline Structure ◽  
Structure And Properties ◽  
X Ray

Ever since the time of Biot and Pasteur, tartaric acid has been the centre of most interesting and fruitful discussions among chemists, physicists and crystallographers. It is hoped that this paper will help to throw light on some of the problems with which its name has so long been associated. 1. Crystalline Structure . The X-ray observations of this work were taken with the aid of a Bragg ionisation-spectrometer and a Coolidge bulb of molybdenum anticathode. The crystals examined were of the ordinary (dextro) variety of tartaric acid.

scholarly journals The crystalline structure of anhydrous racemic acid

1923 ◽  
Vol 104 (725) ◽  
pp. 219-235 ◽  
Keyword(s):  
Tartaric Acid ◽  
Crystalline Structure ◽  
The Other ◽  
Structure And Properties ◽  
Left Handed ◽  
In Virtue Of

This paper is intended to be the continuation of a previous paper on "The Crystalline Structure and Properties of Tartaric Acid” (‘Roy. Soc. Proc., A, February, 1923). Racemic acid, COOH. CH(OH). CH(OH). COOH, is the variety of tartaric acid which is optically inactive by “external compensation,” that is, it is inactive in virtue of the fact that it consists of equal numbers of right- and left-handed molecules of active tartaric acid. It crystallises in two distinct forms, one of which is anhydrous while the other is a monohydrate. But both forms belong to the triclinic pinakoidal class of symmetry, the monohydrate growing at ordinary temperatures and the anhydrous acid above a temperature of about 70° C. This paper deals with the structure of the anhydrous form.

Electron microscopy of crystalline structure in thermotropic random copolymers

1991 ◽  
Vol 49 ◽  
pp. 1054-1055
Author(s):  
Afzana Anwer ◽  
S. Eilidh Bedford ◽  
Richard J. Spontak ◽  
Alan H. Windle
Keyword(s):  
Electron Microscopy ◽  
Crystalline Structure ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Random Copolymers ◽  
Molecular Characteristics ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Identical Monomer ◽  
Periodic Layer

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

Study of the multiplet nature in shpol'skii effect: Host n-heptane crystalline structure by X-ray diffraction and guest coronene position by ESR

1977 ◽  
Vol 22 (2) ◽  
pp. 207-214 ◽  
Author(s):  
A.M. Merle ◽  
M. Lamotte ◽  
S. Risemberg ◽  
C. Hauw ◽  
J. Gaultier ◽  
...  
Keyword(s):  
Crystalline Structure ◽  
X Ray Diffraction ◽  
X Ray

Crystalline Structure and Properties of Carbon Nanofiber Composites Prepared by Melt Extrusion

2007 ◽  
Vol 208 (17) ◽  
pp. 1928-1936 ◽  
Author(s):  
Gang Sui ◽  
Wei-Hong Zhong ◽  
Mike A. Fuqua ◽  
Chad A. Ulven
Keyword(s):  
Crystalline Structure ◽  
Carbon Nanofiber ◽  
Structure And Properties ◽  
Melt Extrusion

X-ray structure and properties of a cyclo[6]pyrrole[3]thiophene

2013 ◽  
Vol 17 (01n02) ◽  
pp. 27-35 ◽  
Author(s):  
Thanh-Tuan Bui ◽  
Aude Escande ◽  
Christian Philouze ◽  
Gianluca Cioci ◽  
Sudip Ghosh ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Structure And Properties ◽  
X Ray ◽  
Expanded Porphyrins ◽  
Pyrrole Derivative

A new member of the cyclo[n]pyrrole class of expanded porphyrins was prepared from the corresponding thiophene-containing terpyrrole precursor through use of a mild electrochemical oxidative procedure. The isolated macrocycle, featuring nine heterocyclic subunits directly connected through their α,α′-positions, is the largest cyclo[n]pyrrole derivative reported to date. The structure obtained via synchrotron radiation-based studies revealed a dimeric arrangement involving individual macrocyclic subunits.

2D X-ray diffraction and molecular modelling of the crystalline structure of polyesters under uniaxial stress

2021 ◽  
pp. 096739112199822
Author(s):  
Ahmed I Abou-Kandil ◽  
Gerhard Goldbeck
Keyword(s):  
Crystalline Structure ◽  
Molecular Modelling ◽  
Three Dimensional ◽  
Uniaxial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Modelling Techniques ◽  
Diffraction Patterns

Studying the crystalline structure of uniaxially and biaxially drawn polyesters is of great importance due to their wide range of applications. In this study, we shed some light on the behaviour of PET and PEN under uniaxial stress using experimental and molecular modelling techniques. Comparing experiment with modelling provides insights into polymer crystallisation with extended chains. Experimental x-ray diffraction patterns are reproduced by means of models of chains sliding along the c-axis leading to some loss of three-dimensional order, i.e. moving away from the condition of perfect register of the fully extended chains in triclinic crystals of both PET and PEN. This will help us understand the mechanism of polymer crystallisation under uniaxial stress and the appearance of mesophases in some cases as discussed herein.

Copper-containing nanocomposites on the basis of isotactic polypropylene and butadiene-nitrile rubber

2021 ◽  
Vol 5 ◽  
pp. 76-81
Author(s):  
N.I. Kurbanova ◽  
◽  
S. K. Ragimova ◽  
N. A. Alimirzoeva ◽  
N. Ya. Ishenko ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Thermal Analyses ◽  
Nitrile Rubber ◽  
Polymer Composition ◽  
Rheological Parameters ◽  
Structure And Properties ◽  
Pressing Method ◽  
X Ray ◽  
High Pressure Polyethylene ◽  
Butadiene Nitrile Rubber

The influence of additives of nanofillers (NF) containing nanoparticles of copper oxides stabilized by a polymer matrix of high-pressure polyethylene (PE) obtained by the mechanochemical method on the structure and properties features of metal-containing nanocomposites based on isotactic polypropylene (PP) and butadiene-nitrile rubber (BNK) is studied by X-ray phase (XRD) and differential thermal analyses(DTA). The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of copper-containing nanoparticles in the PE matrix with the components of the PP/BNK polymer composition. It is shown that nanocomposites based on PP/BNK/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

Sign in / Sign up

Export Citation Format

Share Document