Crystallization Phenomena in Raw Rubber

1942 ◽  
Vol 15 (2) ◽  
pp. 251-264 ◽  
Author(s):  
L. R. G. Treloar
Keyword(s):  
Molecular Structure ◽  
Plastic Flow ◽  
Elastic Recovery ◽  
Quantitative Measure ◽  
Close Correlation ◽  
Breaking Point ◽  
Double Refraction ◽  
Degree Of Orientation ◽  
High Degree

Abstract The process of crystallization in raw rubber held at various extensions at 0° C has been studied by following the accompanying changes in double refraction and in density. From a comparison of the two sets of data, it is concluded that a very low extension produces a relatively high degree of orientation of the axes of the crystallites in the direction of the extension. From 100 per cent extension to the breaking-point, the increase in birefringence with elongation is due almost entirely to an increase in the proportion of crystalline rubber present; over this range the birefringence therefore gives a quantitative measure of the amount of crystallization. From the study of birefringence at 25° and 50° C, it appears that crystallization sets in rather rapidly at a certain intermediate elongation, and then increases continuously to the breaking-point. The observed changes in crystallization show a close correlation with plastic flow and elastic recovery phenomena. The bearing of these observations on the molecular structure of rubber and its mode of crystallization is discussed. It is estimated that the increase of density of rubber on crystallizing is not less than 3.75 per cent.

scholarly journals Representations of Maghrebians' Immigrant Life in France in Two Literary Generations: A Multilevel Cognitive Stylistic Reading of Driss Chraibi’s Les boucs and Azouz Begag’s Le gone du Chaaba

2020 ◽  
Vol 5 (2) ◽  
pp. 163
Author(s):  
Khalid Majhad
Keyword(s):  
Extended Family ◽  
Postcolonial Studies ◽  
Close Correlation ◽  
North African ◽  
Linear Mode ◽  
Chaotic Nature ◽  
Family Based ◽  
High Degree ◽  
Maghrebian Literature ◽  
Frequent Visitor

<em>While political analysts, economists, cultural studies scholars have all been offering insightful analyses of the different matters relating to immigrant life in different parts of the world, this article reaches for a first-hand testimony in two autobiographical novels by two internationally recognized Maghrebian novelists who respectively represent the first and second generations of Maghrebian immigrants in France. In a rather innovative manner, the portrayal of immigrant life in the two novels is analyzed from a cognitive stylistic perspective, and informed by the author’s multiple research viewpoints, those of a Maghrebian literature critic, a francophone postcolonial studies researcher and a frequent visitor to France carrying the concerns of an extended family based there. The interest in style during our close reading of these largely autobiographical narratives is based on the assumption that an author's style is a reflection of their attitude and worldview. Chraibi’s novel Les Boucs (1955) is as timely now as it was in the day of its first appearance for its balanced and largely objective analysis of the sociological, psychological and economic conditions of North African immigrants. Stylistically, Les boucs features a close correlation between its form and content in that the chaotic nature of immigrant life is formally embodied in Chraibi's non-linear mode of writing. In contrast to the bleak picture presented throughout Chraibi's text, Begag's convivial approach oozes hope for his readers who come to realize the futility of continuing to curse the state of deprivation and inequity while there can always be ways setbacks can be turned into opportunities. The study uses a qualitative method of stylistic analysis and applies the two necessary principles of 'contextualization' and 'comprehensiveness' to ensure a high degree of analytical and interpretive validity.</em>

scholarly journals Social Roles as Viewed by Speakers of Non-Cognate Languages.

2020 ◽  
Vol 3 (4) ◽  
pp. 71-83
Author(s):  
Olga Leonidovna Byessonova ◽  
◽  
Keyword(s):  
Native Speakers ◽  
Social Roles ◽  
Men And Women ◽  
Professional Activities ◽  
Male Roles ◽  
The Family ◽  
Degree Of Orientation ◽  
Native Speakers Of English ◽  
The Public Sphere ◽  
High Degree

Introduction. The article addresses the reflection of ideas about gender social roles in the conceptual and linguistic worldview of men and women. Materials and methods. The analysis is based on the material of the linguistic experi-ment conducted with native speakers of such English and Ukrainian. Results. The results of the experiment reveal the differences in the perception by the native speakers of English and Ukrainian of gender social roles. As the analysis of the material shows, in the Ukrainian society, the public sphere is associated to a greater de-gree with the professional activities of men and women, and there is a high degree of orientation of women towards motherhood. In English, outside the family, mainly male roles are defined, and the roles of women are mainly family and are in the sphere of personal, emotional ties. Discussion and Conclusions. The analysis of social roles shows that the Ukrainian lin-guistic community, to a greater extent than the English-speaking, is characterized by an orientation towards the traditional patriarchal family, in which a woman is the keeper of the hearth, the organizer of male consumption, and the man is the owner and head of the family. The results obtained in the course of the experiment enable to establish a systemic cor-relation between the language structure and the social structure, to establish correla-tions between the language phenomena and the gender of the communicants.

scholarly journals The orientation of iron–sulphur clusters in membrane multilayers prepared from aerobically-grown Escherichia coli K12 and a cytochrome-deficient mutant

1980 ◽  
Vol 190 (2) ◽  
pp. 385-393 ◽  
Author(s):  
Haywood Blum ◽  
Robert K. Poole ◽  
Tomoko Ohnishi
Keyword(s):  
Magnetic Field ◽  
Escherichia Coli ◽  
Cytoplasmic Membrane ◽  
Deficient Mutant ◽  
E Coli ◽  
Membrane Particles ◽  
Degree Of Orientation ◽  
High Degree ◽  
Cytochrome Content ◽  
The Magnetic Field

1. Membrane particles prepared from ultrasonically-disrupted, aerobically-grown Escherichia coli were centrifuged on to a plastic film that was supported perpendicular to the centrifugal field to yield oriented membrane multilayers. In such preparations, there is a high degree of orientation of the planes of the membranes such that they lie parallel to each other and to the supporting film. 2. When dithionite- or succinate-reduced multilayers are rotated in the magnetic field of an e.p.r. spectrometer, about an axis lying in the membrane plane, angular-dependent signals from an iron–sulphur cluster at gx=1.92, gy=1.93 and gz=2.02 are seen. The g=1.93 signal has maximal amplitude when the plane of the multilayer is perpendicular to the magnetic field. Conversely, the g=2.02 signal is maximal when the plane of the multilayer is parallel with the magnetic field. 3. Computer simulations of the experimental data show that the cluster lies in the cytoplasmic membrane with the gy axis perpendicular to the membrane plane and with the gx and gz axes lying in the membrane plane. 4. In partially-oxidized multilayers, a signal resembling the mitochondrial high-potential iron–sulphur protein (Hipip) is seen whose gz=2.02 axis may be deduced as lying perpendicular to the membrane plane. 5. Appropriate choice of sample temperature and receiver gain reveals two further signals in partially-reduced multilayers: a g=2.09 signal arises from a cluster with its gz axis in the membrane plane, whereas a g=2.04 signal is from a cluster with the gz axis lying along the membrane normal. 6. Membrane particles from a glucose-grown, haem-deficient mutant contain dramatically-lowered levels of cytochromes and exhibit, in addition to the iron–sulphur clusters seen in the parental strain, a major signal at g=1.90. 7. Only the latter may be demonstrated to be oriented in multilayer preparations from the mutant. 8. Comparisons are drawn between the orientations of the iron–sulphur proteins in the cytoplasmic membrane of E. coli and those in mitochondrial membranes. The effects of diminished cytochrome content on the properties of the iron–sulphur proteins are discussed.

Non-Uniform Chaotic Dynamics with Implications to Information Processing

1983 ◽  
Vol 38 (11) ◽  
pp. 1157-1169 ◽  
Author(s):  
J. S. Nicolis ◽  
G. Meyer-Kress ◽  
G. Haubs
Keyword(s):  
Information Processing ◽  
Characteristic Exponent ◽  
Quantitative Measure ◽  
External Noise ◽  
Strange Attractors ◽  
Pattern Perception ◽  
Small Subset ◽  
Chaotic Flows ◽  
Lyapunov Characteristic Exponent ◽  
High Degree

We study a new parameter - the "Non-Uniformity Factor" (NUF) -, which we have introduced in [1]. by way of estimating and comparing the deviation from average behavior (expressed by such factors as the Lyapunov characteristic exponent(s) and the information dimension) in various strange attractors (discrete and chaotic flows). Our results show for certain values of the control parameters the inadequacy of the above averaging properties in representing what is actually going on - especially when the strange attractors are employed as dynamical models for information processing and pattern recognition. In such applications (like for example visual pattern perception or communication via a burst-error channel) the high degree of adherence of the processor to a rather small subset of crucial features of the pattern under investigation or the flow, has been documented experimentally: Hence the weakness of concepts such as the entropy in giving in such cases a quantitative measure of the information transaction between the pattern and the processor. We finally investigate the influence of external noise in modifying the NUF

scholarly journals IX—investigations on magne-crystallic action III—Further studies on organic crystals

1935 ◽  
Vol 234 (739) ◽  
pp. 265-298 ◽  
Keyword(s):  
Molecular Structure ◽  
Crystal Lattice ◽  
Convenient Method ◽  
Organic Crystals ◽  
Double Refraction ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Benzene Rings ◽  
The Individual ◽  
Ray Methods

In Part I* of this paper a convenient method of measuring the principal magnetic susceptibilities of single crystals was described, and several organic crystals, among others, were studied by this method. The results were discussed particularly in relation to the structure of the molecules and their orientations in the crystal lattice, and it was shown how a correlation of the principal magnetic susceptibilities of the crystal with those for the individual molecules (obtained from measurements on magnetic double-refraction in the liquid state, or from considerations of molecular structure) gives us useful information regarding the orientations of the molecules in the crystal lattice. Indeed, in favourable cases the molecular orientations may thus be determined much more easily, and some of the parameters defining the orientations also more accurately, than by X-ray methods of analysis. Conversely, where the molecular orientations in the crystal lattice are already known from X-ray studies, a knowledge of the principal magnetic susceptibilities of the crystal enables us to obtain the magnetic constants of the individual molecules, which are of interest. For example, it is thus found that as one proceeds from benzene to naphthalene and from naphthalene to anthracene, the numerical increase in susceptibility that occurs, is directed predominantly along the normal to the plane of the benzene rings

Low-Temperature Set as a Measure of State of Vulcanization

1940 ◽  
Vol 13 (2) ◽  
pp. 222-234
Author(s):  
J. H. Fielding
Keyword(s):  
Low Temperature ◽  
Fundamental Property ◽  
Quantitative Measure ◽  
New Product ◽  
Temperature Behavior ◽  
Vulcanized Rubber ◽  
Scientific Equipment ◽  
Artificial Heat ◽  
Water Proof ◽  
High Degree

Abstract In his various patents on vulcanization, Charles Goodyear made several references to the change produced in the low-temperature behavior of rubber. In his earliest patent he stated that vulcanized rubber would not be “injuriously affected by exposure to cold”. The reissues of this patent stated the problem more clearly. “The leading object of my exertions was to render india-rubber capable of resisting the action of heat and cold within the range of atmospheric temperatures…. When compounded with sulfur, by the application of a high degree of artificial heat, I obtained good results, and when compounded with sulfur and the carbonate of lead I obtained the best results.”…. The new product “is water-proof, permanently and highly elastic under all conditions of its use”. Whether Goodyear was referring to the freezing of rubber under tension or under no tension we do not know, but it is probable that he had experienced both effects without distinguishing between them. It is interesting to find now that, one hundred years later, rubber chemists are still looking at this change in low-temperature behavior which he recognized as an effect of vulcanization, and are using the effect as a measure of degree of vulcanization. In recent years the T-50 test has gained considerable popularity as a quantitative measure of the tendency of rubber to freeze under tension. Its popularity is justified, since it can be applied over a broad range of cure and since it measures very precisely a seemingly fundamental property of rubber. It is, however, not the only means of expressing this effect quantitatively. The purpose of the present paper is to demonstrate a simpler method which yields surprisingly precise results, in spite of the fact that none of the usual scientific equipment is used and no measurements other than length measurements are required. Although other papers have approached this subject, none has as yet offered a simple substitute for T-50.

On the laws of polarization and double refraction in regularly crystal­lized bodies. By David Brewster, LL. D. F. R. S. and Edin. In a letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S

1833 ◽  
Vol 2 ◽  
pp. 92-93
Keyword(s):  
Optical Properties ◽  
General Principle ◽  
General View ◽  
Double Refraction ◽  
Primitive Form ◽  
General Law ◽  
Combined Action ◽  
The Right ◽  
Polarization Of Light ◽  
High Degree

In the different inquiries which the author has already laid before this Society, his attention was often directed to the phenomena of regular crystals; but he only lately succeeded in reducing under a general principle all those complex appearances which result from the combined action of more than one axis of double refraction. In this paper Dr. Brewster gives a general view of the present state of our knowledge respecting the double refraction and polarization of light, and afterwards traces the steps which led him to the discovery of the general law. He began his researches by the examination of 165 crystals, in 145 of which he discovered the property of double refraction. In 80 he was able to ascertain whether they had one or more axes; and by examining the tints which they exhibited at va­rious angular distances from the axes, whence the forces emanate, he has been led to a general principle, which embraces all the phenomena and extends to the most complex as well as to the most simple de­velopment of the polarizing forces. This general principle, says Dr. Brewster, is in no respect an empyrical expression of the facts which it represents, nor is it supported by any empyrical data. Founded on the principles of mechanics, it is a law rigorously physical, by which we are enabled to calculate all the tints of the coloured rings, and all the phenomena of double refraction, with as much accuracy as we can compute the motions of the heavenly bodies. The faculty of depolarization, explained by the author in a former paper, has been considered as sufficient indication of two separate images; and upon this principle it has been stated that all crystals are doubly refractive whose primitive form is neither the cube nor the regular octohedron: but this is incorrect; for some of these crystals possess a doubly refracting structure in a high degree. Ad­mitting the statement, however, it could not have been used as a rule for determining whether a crystal refracts doubly or singly; for it is more difficult to detect the primitive form than to examine the optical properties. Tungstate of lime, for instance, would have been reckoned a crystal without double refraction, when Haüy believed its primitive form to be the cube, although it is highly doubly refractive.

A Theory of the Calender Effect in Rubberlike Materials

1945 ◽  
Vol 18 (4) ◽  
pp. 772-779 ◽  
Author(s):  
L. Bilmes
Keyword(s):  
Molecular Structure ◽  
Experimental Data ◽  
Plastic Flow ◽  
Elastic Deformation ◽  
Polyvinyl Chloride ◽  
Mechanical Model ◽  
Temperature Dependent ◽  
Yield Values ◽  
Rubberlike Materials

Abstract The facts relating to the calender effected are briefly stated and illustrated by experimental data obtained with calendered plasticized polyvinyl chloride sheet. The nature of rubberlike deformation is outlined. A theory of the calender effect is proposed in terms of a mechanical model whose relation to molecular structure is indicated. The theory postulates that temperature-dependent yield values be associated with the mechanisms of high elastic deformation and plastic flow.

The Pendulum as a Source of Energy for Plasticity Measurements

1936 ◽  
Vol 9 (4) ◽  
pp. 626-632
Author(s):  
Ira Williams
Keyword(s):  
Plastic Flow ◽  
Parallel Plate ◽  
Elastic Recovery ◽  
Time Factor ◽  
Mathematical Treatment ◽  
Parallel Plates ◽  
Simple Apparatus ◽  
Constant Area ◽  
Rapid Control ◽  
Control Work

Abstract ADVANCEMENT in methods for studying the consistency of rubber during the last 10 years has been confined largely to various modifications of previous tests and to better interpretation of the data obtained. The extrusion plastometer introduced by Marzetti (11) has been modified by Behre (1) to provide a battery of instruments, by Dillon and Johnston (5) to provide more simple apparatus capable of operating at increased rates of shear, and by Dillon (4) to provide an instrument for rapid control work. The parallel-plate plastometer (16) has received numerous modifications of form. DeVries (2) modified the plates to provide a constant area of contact with the rubber. This modification was used by van Rossem and van der Meyden (14) who stressed the necessity of following the elastic recovery as well as the rate of compression. Karrer (8) pointed out the need for controlling the time factor during compression and recovery and has described an instrument (9) with which each measurement requires about 30 seconds. The balance plastometer, which employs parallel plates, was described by Hoekstra (7) and is well adapted to following the elastic recovery after the rubber has been compressed under any conditions of thickness and time. A parallel-plate instrument with interchangeable parts to provide various methods of applying pressure and following recovery was described by Lefeaditis (10). The relation between compression and the extent of recovery has been considered by Dillon (3), who concluded that the measurement of either the compression or the elastic recovery as obtained with the usual parallel-plate plastometer was sufficient if the comparison was confined to a number of batches of a given stock or type of rubber. He also pointed out that elastic recovery depends on the speed of the previous deformation. Hoekstra (6), after considering some of the factors involved in plastic flow, concluded that elastic recovery should be measured only after compression of a rubber to the fixed thickness. The general usefulness of the parallel-plate plastometer has been greatly increased by the mathematical treatment of Peek (13) and Scott (15). A third type of plastometer, consisting of a disk which rotates in compressed rubber while the resistance to shear is measured, has been described by Mooney (12).

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