Properties of Some Synthetic Rubbers

1943 ◽  
Vol 16 (4) ◽  
pp. 857-862
Author(s):  
L. B. Sebrell ◽  
R. P. Dinsmore
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Point Of View ◽  
General Point ◽  
Chain Molecules ◽  
X Ray ◽  
Synthetic Rubber ◽  
The Difference ◽  
Diffraction Patterns ◽  
Long Chain

Abstract X-RAY STRUCTURE OF SYNTHETIC RUBBER In presenting a series of x-ray diagrams of various types of synthetic rubber in comparison with natural rubber, in both the stretched and the unstretched condition, it is our purpose to bring out the fact that the molecular structure of synthetic rubbers is entirely different from that of natural rubber. It is proposed also to review briefly the theories which have been advanced, based on the x-ray analysis of rubber, to account for the elasticity of natural rubber, and to advance the possible reason for the difference shown by the x-ray diagrams of synthetic rubber. At the present time, from the most general point of view, the molecular structure of a rubberlike material is envisaged as a sort of brush-heap structure of entangled long chain molecules. x-Ray diffraction patterns show that, for some rubberlike materials, notable regularities of structure sometimes occur in the tangle of long-chain molecules. It is now realized that these regularities are not essential for rubberlike behavior. Nevertheless their observation and study is important because they afford a unique opportunity for studying the molecular structure of the chains and the molecular rearrangements which occur with the application of stress.

X-Ray Analysis of the Molecular Structure of Rubbers. X-Ray Diffraction of Amorphous Rubber

1952 ◽  
Vol 25 (2) ◽  
pp. 258-264 ◽  
Author(s):  
V. I. Kasatochkin ◽  
B. V. Lukin
Keyword(s):  
Molecular Structure ◽  
Natural Rubber ◽  
Crystalline Phase ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Crystallization Property ◽  
X Ray ◽  
Synthetic Rubber ◽  
Continuous Background ◽  
Diffraction Patterns

Abstract The potentialities of x-ray analysis of the molecular structure of rubbers can be widely extended by measuring the intensities of the amorphous halo and continuous background of scattering in the diffraction patterns of unstretched test-specimens. This method can be applied to the study of the effect of repeated stretching of rubbers. Questions pertaining to the fatigue of rubbers have immense importance now in the performance of rubber products. The methods of determining the crystallization of natural rubber and of measuring the intensity of the amorphous halo for synthetic rubber were employed for investigating the changes of the molecular structure of rubber due to repeated stretching. The crystallization of raw smoked-sheet rubber decreased as a result of fatigue; a similar phenomenon was observed for its vulcanizates. The vulcanizates which were stretched less than 300 per cent lost their crystallization property altogether after fatigue, and, at greater elongations, the content of the crystalline phase greatly decreased (see Figure 1).

The Rubber-like Behavior of an Artificial Substance (Oppanol) when Irradiated with X-rays

1938 ◽  
Vol 11 (4) ◽  
pp. 687-688
Author(s):  
R. Brill ◽  
F. Halle
Keyword(s):  
Natural Rubber ◽  
Normal State ◽  
X Rays ◽  
Organic Substances ◽  
Chain Molecules ◽  
X Ray ◽  
Natural Substances ◽  
Amorphous Sulfur ◽  
Definite Temperature ◽  
Long Chain

Abstract As is known, natural rubber has the property of giving, when stretched, an x-ray fiber diagram, whereas in a normal state the same rubber is amorphous. Numerous other natural substances such as hair and tendon, and artificial substances such as polychloroprene, behave in the same way. However, this effect is not confined to purely organic substances, and it is to be found, for example, in the case of so-called amorphous sulfur and polyphosphornitryl chloride (PNCl2)x. All these substances have the property in common with one another of exhibiting a rubber-like elasticity within a definite temperature range, and of being composed of long-chain molecules.

Tack in Rubber

1964 ◽  
Vol 37 (5) ◽  
pp. 1178-1189 ◽  
Author(s):  
O. K. F. Bussemaker
Keyword(s):  
Natural Rubber ◽  
Theoretical Approach ◽  
Point Of View ◽  
Rubber Industry ◽  
Highly Active ◽  
Synthetic Rubber ◽  
The Usa ◽  
The Subject ◽  
The Difference ◽  
Definition Of

Abstract The expressions tack, tackiness, and stickiness have been in use since the beginning of the rubber industry. During the years their meaning has changed considerably. The first occasion where tackiness was mentioned was in the case of crude natural rubber. The surface of the rubber became tacky or sticky during storage. This phenomenon has been thoroughly discussed in the literature. As a general conclusion it was accepted that both oxidation and depolymerisation occurred. Three factors were reported to be the cause of these processes: light, traces of copper, and manganese. From our point of view we would call this effect stickiness, as we are only interested in the building tack of rubber. In the period when the only rubber was natural rubber and high loadings of highly active fillers were not generally used in compounds, building tack was no problem. Building tack was first mentioned in a publication by Griffith and Jones in 1928. They started their experiments by measuring tack in their search for methods to prevent cotton liners from sticking to unvulcanized rubber. One would have expected much work on the measurement and improvement of tack in Germany and Russia during the development of synthetic rubbers. However, this only proved to be the case in Russia. The first publication available was the translation of an article by Voyutskii and Margolina in 1957. From Voyutskii's work we were able to trace the first article in 1935 by Zhukov and Talmud, who studied the adhesive power of synthetic rubber. In the USA the first theoretical approach to the subject was by Josefowitz and Mark in 1942, who at that time did not realize the difference between stickiness and tack. This difference became clear when lack of tack became the big problem in the use of synthetic rubber. In many cases it was found that addition of resins and softeners gave a very sticky compound which had no building tack at all. The tack problem was first discussed at the ASTM symposium on the application of synthetic rubbers in 1944 by Juve who gave a definition of building tack. From that time, the problem has been studied regularly, especially from the practical side, to find ways and means to improve the building tack of synthetic rubbers.

Observations on the X-Ray Structure of Rubber and the Size and Shape of Rubber Crystallites

1944 ◽  
Vol 17 (3) ◽  
pp. 640-652
Author(s):  
S. D. Gehman ◽  
J. E. Field
Keyword(s):  
Molecular Structure ◽  
Physical Properties ◽  
X Ray Diffraction ◽  
Ray Method ◽  
Chain Molecules ◽  
X Ray ◽  
Rubberlike Material ◽  
Molecular Forces ◽  
Ray Patterns ◽  
Long Chain

Abstract In former times, we used to be painfully aware of the shortcomings and elastic imperfections of Hevea rubber. With its disappearance, we have come to think of it as having an ideal balance in physical properties for a rubberlike material which it has been difficult to approach with synthetic polymers. for this reason, it is still important to investigate the molecular structure of Hevea rubber and to try to understand the characteristics of this structure which are responsible for its physical properties. X-Ray diffraction methods can be applied to the problem of the molecular structure of Hevea rubber and a few synthetic rubbers, such as Butyl rubber and Neoprene, because crystallization occurs upon stretching. A detailed description of the x-ray diffraction results with rubber is available in a review article and need not be repeated here. It should be pointed out that the story obtained from the x-ray structure is not complete because there are important aspects of the structure which are not revealed by this means. It is not possible to measure directly the length of the chain molecules. The nature of the amorphous phase, such as the system of cross-linking of the long chain molecules on vulcanization, does not become evident in x-ray patterns. The physical properties of Hevea rubber must depend on a delicate balance of primary and secondary valence forces. The x-ray method does not permit any direct measurement of these forces but merely shows the geometrical arrangement which results from the molecular forces. Even with these limitations, much valuable information can be secured on the nature of the molecular rearrangements which occur upon stretching. Deductions can be drawn from the x-ray diffraction results regarding the form and spatial relationships of the long chain polymeric molecules and the manner in which they interact under stress. Correlations can then be looked for between the crystallization and the physical properties.

X-Ray Diffraction Patterns of Crystalline Sol Rubber Prepared from Ethereal Solution

1939 ◽  
Vol 12 (3) ◽  
pp. 482-484
Author(s):  
George L. Clark ◽  
Siegfried T. Gross ◽  
W. Harold Smith
Keyword(s):  
Sol Gel ◽  
Crystalline Material ◽  
X Rays ◽  
X Ray Diffraction ◽  
Experimental Procedure ◽  
Chain Molecules ◽  
X Ray ◽  
Measurement And Analysis ◽  
Diffraction Patterns ◽  
Long Chain

Abstract In a previous publication there was reproduced an x-ray diffraction pattern of crystals obtained from a solution, cooled to temperatures between −40° and −50° C, of an ether-gel fraction of rubber from Hevea brasiliensis. Measurements of three strong interferences indicated that the crystals were similar to those of stretched gel rubber and of frozen sol, gel and total rubber. Although many attempts were made at that time, unsatisfactory diffraction patterns were obtained with crystalline ether-sol rubber. The interferences were faint and not suitable for accurate measurement and analysis. Since the crystalline material is bulky and some specimens are more compact than others, it seemed possible that the average number of cell diameters was too small to permit sharp definition, and that more material was required for the examination by x-rays. However, it is not certain that lack of definition was caused by insufficient crystalline rubber. The possibility that parts of the long-chain molecules become crystalline and that parts remain amorphous is not excluded, and might be its cause. Additional work with crystalline sol rubber, using a slightly different experimental procedure and more material than in earlier experiments, finally resulted in a satisfactory pattern.

Infrared spectroscopic study of the YPO4-YCrO4 system

1985 ◽  
Vol 50 (10) ◽  
pp. 2139-2145
Author(s):  
Alexander Muck ◽  
Eva Šantavá ◽  
Bohumil Hájek
Keyword(s):  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Point Of View ◽  
Mixed Crystals ◽  
Crystal Symmetry ◽  
Infrared Spectroscopic Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Spectroscopic ◽  
Diffraction Patterns

The infrared spectra and powder X-ray diffraction patterns of polycrystalline YPO4-YCrO4 samples are studied from the point of view of their crystal symmetry. Mixed crystals of the D4h19 symmetry are formed over the region of 0-30 mol.% YPO4 in YCrO4. The Td → D2d → D2 or C2v(GS eff) correlation is appropriate for both PO43- and CrO43- anions.

Algorithms for the calculation of X-ray diffraction patterns from finite element data

2010 ◽  
Vol 43 (6) ◽  
pp. 1287-1299 ◽  
Author(s):  
E. Wintersberger ◽  
D. Kriegner ◽  
N. Hrauda ◽  
J. Stangl ◽  
G. Bauer
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Point Of View ◽  
X Ray Diffraction ◽  
Displacement Fields ◽  
X Ray ◽  
Si Substrates ◽  
Diffraction Patterns ◽  
Simulation Point ◽  
Ccd Detectors

A set of algorithms is presented for the calculation of X-ray diffraction patterns from strained nanostructures. Their development was triggered by novel developments in the recording of scattered intensity distributions as well as in simulation practice. The increasing use of two-dimensional CCD detectors in X-ray diffraction experiments, with which three-dimensional reciprocal-space maps can be recorded in a reasonably short time, requires efficient simulation programs to compute one-, two- and three-dimensional intensity distributions. From the simulation point of view, the finite element method (FEM) has become the standard tool for calculation of the strain and displacement fields in nanostructures. Therefore, X-ray diffraction simulation programs must be able to handle FEM data properly. The algorithms presented here make use of the deformation fields calculated on a mesh, which are directly imported into the calculation of diffraction patterns. To demonstrate the application of the developed algorithms, they were applied to several examples such as diffraction data from a dislocated quantum dot, from a periodic array of dislocations in a PbSe epilayer grown on a PbTe pseudosubstrate, and from ripple structures at the surface of SiGe layers deposited on miscut Si substrates.

scholarly journals On the stability of unimolecular films. Part II.-The mechanism of film expansion

1929 ◽  
Vol 124 (794) ◽  
pp. 333-343 ◽  
Keyword(s):  
Aqueous Solution ◽  
Condensed State ◽  
Head Group ◽  
Chain Molecules ◽  
X Ray ◽  
Characteristic Area ◽  
The Stability ◽  
Contraction And Expansion ◽  
Long Chain ◽  
Hydrion Concentration

In Part I it was shown that the adhesion of a unimolecular film of a fatty acid to an underlying aqueous solution could be varied by alteration of the Hydrion concentration of the solution. Increasing the alkalinity effected an increase in the adhesional force of the polar beads, and under isothermal con­ditions a film could be converted from the expanded to the liquid condensed and even to the solid condensed state, by causing an increase in these adhesional forces, this process being perfectly reversible. Whilst ionisation of the acid occurs over a bruited range of P H , the alteration in adhesional forces by a change in P H and the effects of such change on the state of the film extend, contrary to the conclusions of Egner and Hägg,* over a much wider range of P H . Since contraction and expansion of the film coincide with an increase decrease respectively in the adhesional forces holding the polar heads to the surface, we may inter that expansion is effected by a gradual tilting of the molecules from the close packed formation existing in the solid condensed state. We have noted that Müller* from X-ray determinations on crystals of fatty acids suggested that it seemed possible that even in a film in the solid condensed state the molecules were already tilted. Objections to this view were raised by Adam, since he found but one characteristic area for long chain molecules in the solid condensed state, which was, with few exceptions, independent of the nature of the head group. He further found that the area in the liquid condensed state*was dependent on the nature of the head group.

Review of Residual Stress Determination and Exploitation Techniques Using X-Ray Diffraction Method

2006 ◽  
Vol 524-525 ◽  
pp. 229-234
Author(s):  
M. Belassel ◽  
J. Pineault ◽  
M.E. Brauss
Keyword(s):  
Residual Stress ◽  
Diffraction Method ◽  
Point Of View ◽  
Stress And Strain ◽  
Stress Determination ◽  
Calculation Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
True Meaning ◽  
The Difference

Although x-ray diffraction techniques have been applied to the measurement of residual stress in the industry for decades, some of the related details are still unclear to many production and mechanical testing engineers working in the field. This is because these details, specifically those associated with the transition between diffraction and mechanics, are not always emphasized in the literature. This paper will emphasize the appropriate calculation methods and the steps necessary to perform high quality residual stress measurements. Additionally, details are given regarding the difference between mechanical and x-ray elastic constants, as well as the true meaning of stress and strain from both diffraction and strain gage point of view. Cases where the material is subject to loading above the yield limit are also included.

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