Aging of Stretched Rubber

1928 ◽  
Vol 1 (1) ◽  
pp. 106-112
Author(s):  
Arthur Kelly ◽  
Bert S. Taylor ◽  
Webster N. Jones
Keyword(s):  
Direct Relationship ◽  
Strain Curve ◽  
Ultra Violet ◽  
The Other ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Test Strips ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Early Stages

Abstract Sunlight aging under tension of many compounds including the following has been investigated: tire tread shoe upper, tube stocks, golf ball thread, jar rubber, solid tire, bathing cap stock, channel rubber. With some of these stocks the sunlight aging as been compared with unstretched samples by Geer oven, Bierer bomb, and ultra-violet light methods. The stretching of the test strips accelerates deterioration in sunlight, ultra-violet light, and Geer oven. Stretched samples have not yet been tested in the Bierer bomb. The rate of deterioration was not proportional to the degree of stretch in any of the stocks in the early stages of exposure. In sunlight there is a critical elongation for each stock at which the deterioration progresses more rapidly than at any other in the early stages of aging. No direct relationship was found between the results of sunlight aging and the other methods employed. Stretched strips aged in ultra-violet light were found to give softer stress-strain curves than the unaged samples, whereas sunlight aging under the same conditions stiffens the stress-strain curve.

scholarly journals Diet and Tuberculosis

1927 ◽  
Vol 26 (2) ◽  
pp. 204-212 ◽  
Author(s):  
Harry Schütze ◽  
S. S. Zilva
Keyword(s):  
Vitamin C ◽  
Guinea Pigs ◽  
Ultra Violet ◽  
The Other ◽  
Cod Liver Oil ◽  
Large Excess ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Fat Soluble Vitamins ◽  
Intraperitoneal Inoculation

Guinea-pigs living on a diet restricted in quantity but not deficient in vitamin C survived inoculation with T.B. but half as long as others which had received a similar diet in abundance.Sodium chaulmoograte did not inhibit the development of the omental tumour that appears in rats after intraperitoneal inoculation with tubercle bacilli.On the other hand, there was some evidence for assuming that a large excess of fat-soluble vitamins in the diet, as supplied by cod-liver oil, inhibits the formation in rats of these tuberculous tumours, but such evidence was by no means conclusive.Similar inhibition of omental infection was obtained on exposing rats to ultra-violet light.Ultra-violet irradiation or the inclusion of large amounts of cod-liver oil in the diet of the rats produced a slight but constant leucocytosis.No evidence was obtained that lack of fat soluble vitamins in their diet renders tubercle infected rats susceptible to tuberculin shock.

scholarly journals Application of the Wilson chamber to the study of spark discharge

1935 ◽  
Vol 148 (864) ◽  
pp. 446-453 ◽  
Keyword(s):  
Ultra Violet ◽  
Spark Discharge ◽  
Cloud Chamber ◽  
The Other ◽  
Present Stage ◽  
Expansion Chamber ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Negative Point ◽  
Kerr Cell

The usual methods of investigating the problems related to the phenomenon of spark discharge may be classified into two kinds. The first is to measure the potential and current or their variations with respect to time, which may be called "electrical." By this means we know only the signals transmitted from the spark. The second method is optical, to which belong the photographic and spectrographic investigations as well as the method using a Kerr cell. These methods give us information on the spark itself, but they are confined to the problems accompanied with the emission of light. For observing a process of discharge that does not accompany any luminous phenomenon, the use of Professor Wilson's cloud chamber seems to be the only method suitable for the for the purpose at our present stage of knowledge. As a matter a fact, already in 1899 Wilson, using an expansion chamber of the earlier type, had investigated the formation of ion clouds by the positive and negative point discharges. Since then no communication seems to have been published on the formation of ion clouds by an electrical break-down process until recently, when the present authors and Snoddy and Bradley published independently the reports of their experiments of this subject. Several years ago one of the present authors, under the direction of Professor T. Terada, engaged, in a study concerning the form and structure of long electric sparks. He then succeeded, using a quartz-fluorite ions, in taking a photograph of the brush discharges immediately preceding the main spark. This preceding discharge is rich in ultra-violet light, and more complicated and extended in its form than the succeeding main spark, appearing as appendages to the luminous spark track. This result led him to look for the other form of discharge which cannot be photographed even with the quartz-fluorite lens. Then, on the suggestion of Professor T. Terada, he tried to take a Wilson photograph of ions produced by a spark, but did not succeed in obtaining a satisfactory one. Later on, in the course of conversation with Professor Wilson at Cambridge he was given a great deal of advice on this problem and decided to take up this subject again.

Studies on embryonic determination of the harlequin-fly, Chironomus dorsalis. II. Effects of partial irradiation of the egg by ultra-violet light

Development ◽  
1964 ◽  
Vol 12 (1) ◽  
pp. 89-100
Author(s):  
Hideo Yajima
Keyword(s):  
Ultra Violet ◽  
The Other ◽  
Centrifugal Forces ◽  
Ultra Violet Light ◽  
Violet Light

In an earlier study (Yajima, 1960) of centrifugation of the egg of Chironomus dorsalis, the author obtained various types of double malformation (double cephalon and double abdomen) which are correlated with the orientation of the egg at the time of centrifugation. As a result the author proposed (1) that the embryonic character of Chironomus was determined by two formative localities; one located in the anterior end of the egg and determining the cephalic structures, and the other located in the posterior end and having a tendency toward abdominal development, (2) that the thoracic structures are determined as the result of interaction between the two localities and, finally, (3) that such localities must be carried by a substratum not moved by centrifugal forces of less than 27,000 g.

Hyperthermia Induced Polyphosphate Changes in Propionibacterium acnes as Studied by 31P NMR

1989 ◽  
Vol 44 (1-2) ◽  
pp. 45-48 ◽  
Author(s):  
B. Kjeldstad ◽  
A . Johnsson ◽  
K. M. Furuheim ◽  
A . Schie Bergan ◽  
J. Krane
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Propionibacterium Acnes ◽  
Ultra Violet ◽  
The Other ◽  
Hyperthermia Treatment ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Increasing Temperature ◽  
Induced Changes

Abstract The polyphosphate component in MP NMR spectra of the Gram-positive Propionibacterium acnes increased after hyperthermia treatment. The cells were exposed to temperatures in the interval from 15 °C to 45 °C. The amount of polyphosphate increased with increasing temperature. There were no temperature induced changes in the other phosphorous components seen in the spectra with exception of a decrease in ATP for higher temperatures. The increase in polyphosphates was less than that obtained from cells irradiated by near ultra-violet light.

A Mathematical Treatment of a Theory of Rubber Structure

1935 ◽  
Vol 8 (1) ◽  
pp. 23-38
Author(s):  
T. R. Griffith
Keyword(s):  
Elastic Modulus ◽  
Plastic Flow ◽  
Strain Curve ◽  
The Other ◽  
Stress Axis ◽  
Mathematical Treatment ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Joule Effect ◽  
Vulcanized Rubber

Abstract A brief consideration of the work that has been done on the structure of rubber convinces, one that the elasticity is wholly or at least mainly explained by a consideration of the kinetics involved. The fact that when a strip of stretched rubber, one end of which is free, contracts when it is warmed, contrary to the behavior of most bodies, and that it becomes warmed on stretching, commonly known as the Gough-Joule effect, pp. 453–461, would lead one to suspect .that there is a connection between the kinetic energy of the rubber molecule and its elasticity. Lundal, Bouasse, Hyde, Somerville and Cope, Partenheimer and Whitby and Katz have reported observations, principally stress-strain curves, which show that vulcanized rubber has a lower modulus of elasticity at higher temperatures, i. e., it becomes easier to stretch as the temperature is raised. On the other hand, Schmulewitsch, Stevens, and Williams found that the elastic modulus increases with the temperature. Williams shows that the softening of vulcanized rubber with rise of temperature is due to an increase of plasticity. In order to get rid of plastic flow, he first stretches the specimen several times to within about 50 per cent of its breaking elongation, and then obtains an autographic stress-strain curve of the rubber stretched very quickly. He finds that in this case the rubber actually becomes stiffer with rise of temperature, increasing temperatures causing the stress-strain curves to lean progressively more and more toward the stress axis. He concludes that rise of temperature has two effects, one a softening due to increase of plasticity, rendering plastic flow more easy, the other an actual stiffening of the rubber due to rise of temperature. It is not easy to explain the latter effect on any theory which does not take kinetics into account.

scholarly journals The mechanism of plastic deformation of crystals. Part II.—Comparison with observations

1934 ◽  
Vol 145 (855) ◽  
pp. 388-404 ◽  
Keyword(s):  
Elastic Limit ◽  
Large Range ◽  
Strain Curve ◽  
Pure Metal ◽  
The Other ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Essential Characteristic ◽  
Small Strains ◽  
Plastic Stress

According to the theory give in Part I the strain-hardening or plastic stress strain curve for a pure metal should be parabola. In figs. 1, 2, and 3, Part I, Parabolas are drawn, the parameters being chosen so that they lie as close as possible to the points which represent actual observations. It will be seen that for aluminium and gold the agreement is good. For a single crystal of copper the agreement is not good, but, on the other hand, the plastic stress-strain curve for polycrystalline specimens of copper which is shown in fig. 1 is very nearly parabolic over a large range. The observations for iron seem to show that there is a small finite elastic limit, i. e. , S T may be finite. Parabolas corresponding with the existence of a small elastic limit and with no elastic limit have been drawn. It seems that the observed points lie rather closer to the former curve. In any case, the observed curves have the essential characteristic of the theoretical ones that they are very steep at small strains, but get less and less steep as the strain increases.

Properties of Higher Polymers in Solution. III. The Action of Ultra-Violet Light on Dissolved Rubber

1936 ◽  
Vol 9 (4) ◽  
pp. 570-572 ◽  
Author(s):  
Kurt H. Meyer ◽  
Cesare Ferri
Keyword(s):  
Physical Properties ◽  
Wave Length ◽  
Ultra Violet ◽  
The Other ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Ultra Violet Radiation ◽  
Gutta Percha ◽  
Other Hand ◽  
Violet Radiation

Abstract The action of ultra-violet radiation on rubber has been the object of a long series of investigations. According to van Rossem, rubber is depolymerized under the action of light. Asano on the other hand thinks that ultra-violet light, is able to bring about either polymerization or depolymerization according to its wave-length. More recently Dogadkin and Pantschenkov have carried out experiments in an atmosphere of nitrogen, during the course of which they have found a strong diminution in the viscosity. From this fact they have concluded that light is able to cause depolymerization and micellar degradation. We have undertaken a study of the action of ultra-violet light on rubber in order to prove whether the double cis-linkages of rubber undergo a transposition into trans-linkages, for numerous instances are known where light causes these cis-trans-transpositions. In the case of rubber, one should obtain, therefore, either a hydrocarbon of the gutta-percha type or, if light causes a sort of cis-trans-equilibrium, a hydrocarbon with double cis-linkages distributed irregularly. In our experiments we were extremely careful to exclude oxygen, since some years ago Henri proved that ultra-violet light activates greatly the oxidation of rubber. On the other hand it is known that oxidation causes a diminution in the length of the chains which modifies considerably the physical properties, for example, the viscosity, and which may mask the effect produced by light.

Experiments on the Electrical Phenomena produced in Gases by Röntgen Rays, by Ultra Violet Light, and by Uranium

1897 ◽  
Vol 21 ◽  
pp. 393-428
Author(s):  
Lord Kelvin ◽  
J. Carruthers Beattie ◽  
M. S. de Smolan
Keyword(s):  
Ultra Violet ◽  
Glass Tube ◽  
The Other ◽  
Electric Filter ◽  
Axial Line ◽  
Rubber Tubing ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Suction Pipe ◽  
Series Of Experiments

§ 1. To test whether or not the Röntgen rays have any electrifying effect on air, the following arrangement was made.A lead cylinder 76 cms. long, 23 cms. diameter, was constructed; and both ends were closed with paraffined cardboard, transparent to the Röntgen rays. Outside the end distant from the electrometer (see diagram 1) a Röntgen lamp was placed. In the other end two holes were made, one in the middle, through which passed a glass tube (referred to below as suction pipe) of sufficient length to allow the end in the lead cylinder to be put into any desired place in the cylinder. By means of this, air was drawn through an electric filter by an air pump. The other hole, at a little distance from the centre, contained a second glass tube by which air was drawn through india-rubber tubing from the open-air quadrangle outside the laboratory.In one series of experiments the end of the suction pipe was kept in the axial line of the lead cylinder at various points 10 cms. apart, beginning with a point close to the end distant from the Röntgen lamp.In every case the air drawn through the filter was found to be negatively electrified when no screen or an aluminium screen was interposed between the Röntgen lamp and the near end of the lead cylinder. The air was found not electrified at all, or very slightly negative, when a lead screen was interposed.

A Contribution to the Characterization of the Plastic-Elastic State

1939 ◽  
Vol 12 (4) ◽  
pp. 799-804 ◽  
Author(s):  
E. Rohde
Keyword(s):  
Characteristic Property ◽  
Strain Curve ◽  
The Other ◽  
Elastic State ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Other Hand ◽  
Puzzling Problem

Abstract The manner in which vulcanized rubber can be deformed and yet return almost completely to its original dimensions after the stress is released is a unique and characteristic property. Technically the problem in testing rubber is to evaluate this property and to define it in terms of the factors which are concerned. To define completely this property of rubber whereby it is susceptible to deformation, it is necessary to know the stress, the elongation, the energy expended, the energy lost, the time and the temperature. The stress, elongation and energy expended are closely related and are characterized by the stress-strain curve, which in turn depends on the time and temperature. In addition, it must be borne in mind that rubber can be deformed either by tension or by pressure, but this will not be discussed further here. On the other hand a rather puzzling problem will be considered, the solution of which brings out the fact that the three variables involved in any deformation, viz.: (1) The time or frequency. (2) The temperature. (3) The interrelated factors: stress, elongation and energy expended, must be varied considerably in order to characterize the phenomena of deformation and that when this is done, unexpected results are obtained.

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