Flex Life and Crystallization of Synthetic Rubber

1944 ◽  
Vol 17 (2) ◽  
pp. 398-403 ◽  
Author(s):  
J. H. Fielding
Keyword(s):  
Natural Rubber ◽  
Experimental Work ◽  
Thermal Effects ◽  
X Ray ◽  
The Past ◽  
Synthetic Rubber ◽  
New Material ◽  
The Subject ◽  
And Performance ◽  
Ray Patterns

Abstract The crystalline structure of stretched natural rubber has been the subject of much experimental work in the past. A great deal of this has been devoted to the more theoretical aspects, such as x-ray patterns, thermal effects, and volume change. It is now known that neither Buna-N nor GR-S has a fiber diagram when stretched and that Butyl-B and Neoprene do have such patterns. Since the industry is now in the process of changing from natural rubber to GR-S, it is of interest to see just what this lack of crystallinity means from a compounding and performance standpoint. It is possible that many of our ideas based on rubber must change, that GR-S must be considered to be a new material, and that radical changes in formulation and construction must be made.

scholarly journals The effect of thermal agitaion on atomic arrangement in alloys—II

1935 ◽  
Vol 151 (874) ◽  
pp. 540-566 ◽  
Keyword(s):  
High Temperatures ◽  
Experimental Work ◽  
Low Temperatures ◽  
Theoretical Treatment ◽  
X Ray ◽  
Atomic Arrangement ◽  
Metal Atoms ◽  
Theoretical Investigations ◽  
The Subject ◽  
Kinetics Of

The transformations between a disordered arrangement of the metal atoms in an alloy at high temperatures and an ordered arrangement of the atoms at low temperatures have formed the subject of many experimental and theoretical investigations. The process of segregation into regular positions was first envisaged by Tammann in 1919. It was proved to take place in the gold-copper and other alloy systems by Johannson and Linde by X-ray investigation. Theoretical treatments of the problem have been given in papers by Borelius, Johannson, and Linde, Gorsky, and Dehlinger and Graf, and the same authors have published a large amount of experimental work on this type of transformation in the Au-Cu system. Some experiments on order-disorder transformations in the Fe-Al system, carried out by Bradley and Jay in this laboratory, led us to examine the kinetics of the change, and we recently published a paper in these Proceedings dealing with various aspects of it. Since publishing this paper, we have become aware that our theoretical treatment has in several respects a closer parallelism to those of Borelius, Gorsky, and Dehlinger than we realized at the time of writing it. We shall try to make a proper acknowledgment in the present paper.

Science and Technology of Reclaimed Rubber

1967 ◽  
Vol 40 (1) ◽  
pp. 217-237 ◽  
Author(s):  
D. S. le Beau
Keyword(s):  
Natural Rubber ◽  
Polymer Processing ◽  
Raw Material ◽  
Plastic State ◽  
Substantial Part ◽  
Process Conditions ◽  
Fibrous Materials ◽  
The Past ◽  
Synthetic Rubber ◽  
Mechanical Handling

Abstract Developments in the rubber reclaiming industry are closely related to those in the rubber industry in general. The vulcanized rubber produced by the latter becomes in time the raw material used by the former. Although not superficially obvious, there has been considerable change in the reclaiming industry in the past two decades, required by the introduction of large proportions of synthetic rubber. Since this occurs both alone and in blends with natural rubber, reclaiming of SBR had to be studied in detail so that processes could be adjusted to give approximately the same viscosity from synthetic rubber and from natural, retaining existing procedures for fiber removal and mechanical handling as much as possible. It would have been economically impossible for reclaimers to use any process which required segregation and separate disposal of a substantial part of their raw material. The machinery used in the production of reclaim, and the reclaiming processes used today, are for the major part still the same as used before. The object of reclaiming vulcanized scrap is still the same, i.e., the breakdown (depolymerization) of the scrap to a plastic state which will permit reuse of it in the current rubber processing machinery for the manufacture of new goods. This breakdown is achieved by the application of energy. The type of energy is fundamentally irrelevant, but economics today dictate that it be heat, with partial exclusion of the oxidizing atmosphere, and therefore most of today's reclaim production is carried out in steam. One new continuous reclaiming process was developed during the last fifteen years which relies on electric energy to provide the necessary heat and working of the vulcanized scrap. A fundamental change in requirements of reclaim was also brought about once the synthetic rubber production had proceeded to the point where it was commercially possible to assign more detailed specifications which described the polymer processing behavior limits—a feat not previously achieved for commercial natural rubber. This type of specification was carred over to a considerable extent into the production and sale of today's reclaim. All in all, the extensive research and polymer knowledge which were acquired for the successful production of synthetic rubber have resulted in a much greater control in the production of reclaim and a much greater understanding of the reactions occurring in polymers during reclaiming. Because vulcanized scrap usually contains extraneous material (fiber) which must be removed during reclaiming the process conditions have in the past been selected primarily to accomplish this removal and were not those best suited for the actual reclaiming reaction. Progress has been made during these last years in removing the fibrous materials before reclamation, thereby permitting conditions in the devulcanization cycle to be determined by the actual needs of the vulcanized scrap.

scholarly journals Evaluation of Radiographers’ Knowledge, Attitudes, and Performance Regarding Gonadal Shielding in Diagnostic Radiology Examinations: Southern Khorasan Province Hospitals of Iran

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Nima Hamzian ◽  
Saeed Asadian ◽  
Asiye Golestani ◽  
Hassan Zarghani
Keyword(s):  
Ionizing Radiation ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
X Ray ◽  
A Value ◽  
Pelvic Area ◽  
Pelvic Radiography ◽  
The Subject ◽  
And Performance

Background: Nowadays, ionizing radiation is increasingly used in medicine. One of the most frequent X-ray examinations is pelvic radiography. Gonads are susceptible in the pelvic area. Gonadal shielding (GS) is a useful method to reduce the received dose by gonads. Despite the benefits of using gonadal shielding, it is rarely used by radiographers. Methods: This cross-sectional study was carried out in ten governmental hospitals with 300 radiographs. Results: The radiographers’ knowledge of using GS had a value equal to 59.1%. However, the radiographers did not have enough information on the subject, although their awareness about the significance of GS was acceptable. Conclusions: Although the radiographers believed in the necessity of using GS for pelvic, abdominal, and spine examinations, they used no shields.

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).

Crystallization of Natural Rubber

1967 ◽  
Vol 40 (3) ◽  
pp. 25-47 ◽  
Author(s):  
Norman Bekkedahl
Keyword(s):  
Glass Transition ◽  
Natural Rubber ◽  
Research Work ◽  
Scientific Research ◽  
Melting Transition ◽  
National Bureau ◽  
Great Honor ◽  
The Past ◽  
The Subject ◽  
Published Paper

Abstract It is, indeed, a very great honor to have been chosen as the Charles Goodyear Medalist for 1967, and I very much appreciate the opportunity of coming here to tell you about some of the research work in the field of rubber with which I have been associated for a number of years. The bylaws of the Division of Rubber Chemistry, A.C.S., require that the recipient of this award deliver a lecture before the Division on a subject that is related to the elastomer field and presented in accordance with the contribution for which the medal is awarded. It should, therefore, be quite appropriate for me to discuss one of my favorite subjects, the crystallization of natural rubber. My first thought was to talk on a broader subject, transitions in rubber, which would have included the glass transition, but such a paper was found to be much too long. Even the subject of the crystallization and melting transition is so broad that only a very condensed version can be given here today. In fact, the references for a proper review would run into the hundreds, so therefore I decided to restrict the paper to cover only the research work that has taken place in our own laboratories of the National Bureau of Standards. I should like to consider this award as one given not to me alone but rather to the group of us at the National Bureau of Standards who have been conducting scientific research on rubber during the past few decades. The names of most of these investigators who have made contributions in the area of rubber crystallization will appear in the bibliography of the published paper, but I should like at this time to name a few of the senior scientists whose work we shall discuss here.

Earthquake Response Monitoring and Structural Analysis of Traditional Japanese Timber Temple

2013 ◽  
Vol 778 ◽  
pp. 823-828
Author(s):  
Kaori Fujita ◽  
Eunmi Shin ◽  
Akito Ibaraki ◽  
Masashi Sanuki
Keyword(s):  
Structural Analysis ◽  
Seismic Behavior ◽  
Cultural Property ◽  
Response Monitoring ◽  
X Ray ◽  
The Past ◽  
Kanto Earthquake ◽  
The Subject ◽  
The Difference ◽  
The Temple

This paper introduces the recent attempts to clarify the seismic behavior of traditional timber architecture. The subject of the research is a timber temple, Kencho-ji, in Japan, designated as important cultural property. The temple was affected by the Great Kanto Earthquake 1923. There are two main halls in the Kencho-ji temple, and one of them collapsed while the other slightly inclined. The two main halls have similar structures, and stand next to each other. The authors have been trying to clarify the reason for the difference in the damage for the past ten years through on-sight measurement, micro tremor test, earthquake monitoring and structural analysis. As there is very few information concerning the hidden detail of the joints, recently the authors have operated X-ray inspection. The paper introduces the result of the X-ray test and the structural analysis using the result of the newly revealed hidden joint is discussed.

The Past in the Present? A Response to Stan's Cafe's Revival of ‘The Carrier Frequency’

2000 ◽  
Vol 16 (1) ◽  
pp. 97-99
Author(s):  
Frances Babbage
Keyword(s):  
Carrier Frequency ◽  
The Past ◽  
Theatre Company ◽  
Theatre Studies ◽  
The Subject ◽  
And Performance ◽  
The University

The premiere of The Carrier Frequency took place in 1984, the result of a collaboration between Leeds-based Impact Theatre Cooperative and the novelist Russell Hoban. Impact was founded in 1978 by Claire MacDonald, Pete Brooks, Steve Schill, Graeme Miller, Tyrone Huggins, and Richard Hawley, with Nikki Johnson and Heather Ackroyd joining in subsequent years. Many companies since have cited Impact as a major inspiration, with The Carrier Frequency in particular achieving almost mythic status. Today, Impact has long since disbanded, and little documentation of their work remains to enable their legacy to be passed on. In April 1999, the theatre company Stan's Cafe (none of whom had seen the original show) decided to restage The Carrier Frequency as part of Birmingham's ‘Towards the Millennium’ festival; in association with this project, a symposium was held on the subject of ‘Archaeology, Repertory, and Theatre Inheritance’. What follows is a personal response to the experience of attending the symposium and performance, and records a variety of attitudes towards myth-making, re-creation, and the potential and problems of documentation. Frances Babbage lectures in Theatre Studies at the University of Leeds.

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.

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.

Chemical Derivatives of Synthetic Isoprene Rubbers

1947 ◽  
Vol 20 (3) ◽  
pp. 664-688
Author(s):  
I. D. D'Ianni ◽  
F. J. Naples ◽  
J. W. Marsh ◽  
J. L. Zarney
Keyword(s):  
World War Ii ◽  
Natural Rubber ◽  
Reaction Products ◽  
World War ◽  
The Past ◽  
Chemical Derivatives ◽  
The Subject ◽  
Intensive Investigation ◽  
Derivatives Of ◽  
Rubber Product

Abstract Natural rubber was the subject of intensive investigation with respect to its chemical reactions and the preparation of commercially useful derivatives. General reviews in this field have been written by Fisher, Schidrowitz, Jones, Sibley, Memmler, Dawson and Schidrowitz, and Farmer. Before World War II several of these reaction products, such as rubber hydrochloride (Pliofilm), isomerized rubber (Pliolite), and chlorinated rubber (Parlon), had been marketed successfully. During the past five years drastic restriction of the commercial use of natural rubber for chemical derivatives prompted the study of synthetic rubbers for this purpose. Endres recently reported on chlorinated and cyclized synthetic lubbers, with special emphasis on GR-S as the starting material. This paper deals particularly with derivatives of polyisoprene and other isoprene-containing synthetic rubbers which behave chemically very much like natural rubber because of the similarity in structure. It is shown that GR-S and other butadiene-containing synthetic rubbers, under the same conditions, are either nonreactive or behave differently. Because of its similarity to the natural rubber product, isomerized synthetic polyisoprene has been designated Pliolite S-1. Chlorinated synthetic polyisoprene is referred to as Pliochlor.

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