The Fusion Curves of Rubber and Gutta-Percha

1938 ◽  
Vol 11 (4) ◽  
pp. 658-660
Author(s):  
Kurt H. Meyer
Keyword(s):  
Melting Point ◽  
Kinetic Theory ◽  
Free Rotation ◽  
Gutta Percha ◽  
Set Up ◽  
Thermodynamic Probability ◽  
Primary Valence

Abstract It is already known that many rubber-like substances such as elastic sulfur and polyphosphornitryl chloride show crystal interferences when stretched, and that these interferences disappear again when the tension is removed. This shows that the melting point is increased by traction, and von Susich actually determined roentgenographically the relation between the melting point and deformation and thus obtained a “fusion curve.” This phenomenon can be explained by means of the kinetic theory of the elasticity of rubber. According to this theory, the stress set up in rubber when stretched depends on the fact that heat motion tends to restore to the statistically favorable, crooked, and hence shorter form, the primary valence chains which have been extended by traction and thus are in a statistically less probable position and form. For, as a result of free rotation, it is possible to have many curved forms but only one maximum elongated form; the thermodynamic probability β, and on account of the relation: S=R ln β, the entropy S as well, are consequently greater in the unstretched than in the stretched state.

scholarly journals The Effect of Non-Hydrostatic Stress on Intergranular Water Veins and Lenses in Ice

1972 ◽  
Vol 11 (61) ◽  
pp. 81-101 ◽  
Author(s):  
J. F. Nye ◽  
S. Mae
Keyword(s):  
Melting Point ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Pure Shear ◽  
Triple Junctions ◽  
Polycrystalline Ice ◽  
Glacier Ice ◽  
Set Up ◽  
Ice Water

AbstractPolycrystalline ice at the melting point has been observed in the laboratory to contain veins of water at the places where three grains meet. Under uniaxial compression lenticular water inclusions appeared at grain boundaries perpendicular to the stress, while the nearby vein began to freeze. A similar effect occurred in tension on grain boundaries parallel to the stress. When the stress on the plane of the boundary was a pure shear stress, no effect was observed. The water lenses produced by stress increased in size and decreased in number after the stress was removed. The effect under compression is explained quantitatively by the combined effects of curvature and pressure on the melting point of an ice–water interface. The rate of formation of the lenses and of their coarsening is greatly reduced by the internal pressures set up in the lenses as a result of expansion on freezing and contraction on melting; transient creep to accommodate volume changes is an essential part of the process. The effect in a grain boundary under tension may arise from pressure caused by sliding on other grain boundaries; it was absent in a bicrystal.It is concluded that internal melting and freezing at grain boundaries and veins will occur in temperate glacier ice, with some effect, not discussed here, on its permeability to water. Any pure solid at its melting point which has a dihedral angle for the liquid phase in contact with a grain boundary between 0° and 60° should show similar behaviour, in that non-hydrostatic stress should cause liquid to move away from triple junctions between grains and into grain boundaries. There may be implications for the Frank theory of the upwelling of melt fluid in the Earth’s upper mantle.

Growth of an 8-hydroxyquinoline single crystal by a modified Czochralski growth technique, and crystal characterization

CrystEngComm ◽  
2018 ◽  
Vol 20 (5) ◽  
pp. 624-630 ◽  
Author(s):  
Sonu Kumar ◽  
Binay Kumar
Keyword(s):  
Melting Point ◽  
Single Crystal ◽  
Organic Compounds ◽  
Hirshfeld Surface ◽  
Czochralski Growth ◽  
Growth Technique ◽  
Fingerprint Plots ◽  
Set Up ◽  
Crystal Characterization

Piezoelectric 8-hydroxyqunoline crystal was grown by modified Czochralski set-up, designed for low melting point organic compounds. Hirshfeld surface and fingerprint plots were generated.

scholarly journals The Effect of Non-Hydrostatic Stress on Intergranular Water Veins and Lenses in Ice

1972 ◽  
Vol 11 (61) ◽  
pp. 81-101 ◽  
Author(s):  
J. F. Nye ◽  
S. Mae
Keyword(s):  
Melting Point ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Pure Shear ◽  
Triple Junctions ◽  
Polycrystalline Ice ◽  
Glacier Ice ◽  
Set Up ◽  
Ice Water

AbstractPolycrystalline ice at the melting point has been observed in the laboratory to contain veins of water at the places where three grains meet. Under uniaxial compression lenticular water inclusions appeared at grain boundaries perpendicular to the stress, while the nearby vein began to freeze. A similar effect occurred in tension on grain boundaries parallel to the stress. When the stress on the plane of the boundary was a pure shear stress, no effect was observed. The water lenses produced by stress increased in size and decreased in number after the stress was removed. The effect under compression is explained quantitatively by the combined effects of curvature and pressure on the melting point of an ice–water interface. The rate of formation of the lenses and of their coarsening is greatly reduced by the internal pressures set up in the lenses as a result of expansion on freezing and contraction on melting; transient creep to accommodate volume changes is an essential part of the process. The effect in a grain boundary under tension may arise from pressure caused by sliding on other grain boundaries; it was absent in a bicrystal.It is concluded that internal melting and freezing at grain boundaries and veins will occur in temperate glacier ice, with some effect, not discussed here, on its permeability to water. Any pure solid at its melting point which has a dihedral angle for the liquid phase in contact with a grain boundary between 0° and 60° should show similar behaviour, in that non-hydrostatic stress should cause liquid to move away from triple junctions between grains and into grain boundaries. There may be implications for the Frank theory of the upwelling of melt fluid in the Earth’s upper mantle.

Migration and Blooming of Waxes to the Surface of Rubber Vulcanizates

1981 ◽  
Vol 54 (2) ◽  
pp. 255-265 ◽  
Author(s):  
S. H. Nah ◽  
A. G. Thomas
Keyword(s):  
Melting Point ◽  
Ambient Temperature ◽  
Driving Force ◽  
Volume Fraction ◽  
Adequate Explanation ◽  
Practical Applications ◽  
Elastic Stresses ◽  
Factors Influencing ◽  
Set Up

Abstract The model proposed in this paper appears to give an adequate explanation for the magnitude of the blooming rates observed. The driving force is due to elastic stresses set up around the precipitated wax particles and thus the blooming rate is influenced quite strongly by the modulus of the rubber. On the basis of this mechanism it would be expected that unvulcanized rubber would show little blooming, and this is in accord with general observations on such materials. The solubility of the wax is an important parameter and, because of its sensitivity to temperature, the ambient temperature and the melting point of the wax will be important factors influencing the blooming in practical applications. The precipitation of the wax has been assumed to occur at imperfections in the material. The source of these is not yet clear, although impurities could clearly be important. The values that have to be assumed for the volume fraction of these seeding sites, about 10−3, is not unreasonable in general magnitude for impurity concentrations.

scholarly journals Local difference of pressure near an obstacle in oscillating water

1915 ◽  
Vol 91 (631) ◽  
pp. 405-410
Keyword(s):  
Gutta Percha ◽  
Local Difference ◽  
The Mean ◽  
Pressure Indicators ◽  
Level I ◽  
Set Up

In a former paper I showed that when a barrier fits tightly against the sides and across the bottom of a vessel of oscillating water (1) a vortex forms against each side of the barrier in turn as it becomes the lee side; (2) this vortex never forms while the water is attaining to the mean level, but only while it is falling below and rising above that level. I suggested that such vortices were due to the conjunction of the mainstream flowing over the barrier with opposing local streams created by local differences of pressure set up in the neighbourhood of the barrier by the oscillating water. Exception was taken to this explanation, and also, later, to experiments made with a box partially covered with thin gutta percha diaphragms, for the purpose of proving the formation of the local differences of pressure alluded to. The object of the present paper is to give an account of further experiments carried out for this same purpose, with pressure indicators which are free from the objection urged against the diaphragms. viz: that they themselves might cause variations in the distribution of pressure.

scholarly journals Wind structure and evaporation in a turbulent atmosphere

1934 ◽  
Vol 146 (858) ◽  
pp. 701-722 ◽  
Keyword(s):  
Kinetic Theory ◽  
Plane Surface ◽  
Turbulent Medium ◽  
Lower Atmosphere ◽  
Collision Dynamics ◽  
Disturbing Force ◽  
Wind Structure ◽  
Diffusion Phenomena ◽  
Set Up ◽  
Preliminary Consideration

1-It is now generally recognized that in a turbulent medium, such as the lower atmosphere, the processes of the diffusion of mass, heat, and momentum are dominated by the action of eddies in the wind. The exact mechanism by which the typical frictional and diffusion effects are set up by the turbulence is still obscure, and at the present time there appears to ire little hope of the presentation of a comprehensive theory of turbulent motion. The object of the present paper is to set forth a theory which, while admittedly non-exact and based partly upon an empirical assumption, appears to afford a satisfactory basis for the preliminary consideration of the allied problems of wind structure and the natural evaporation from a freely exposed plane surface in the lower atmosphere. 2-It is noticeable that most of the theories of turbulence which have been advanced treat the diffusion phenomena by means of a model which is suggested by the kinetic theory of gases. The eddies are regarded as distinct masses of fluid which behave like the molecules of the kinetic theory in that they are assumed to move along a hind of "free path," and thereby to transfer mass, heat momentum from one layer of the fluid to another by a process which is regarded as being substantially identical with that described by the collision dynamics of the kinetic theory. Briefly, it is assumed that a certain mass of fluid, of dimensions small compared with those of the total volume of fluid under consideration, breaks away from its surroundings under the influence of some mechanical or thermal disturbing force, and moves to another region of the medium, carrying with it a content of mass, heat, and momentum topical of the layer from which it originated. Having moved a certain distance (the Mischungsweg of Prandtl) the eddy is then conceived to mix instantaneously with the surrounding fluid, much in the same manner as a molecule transfers a portion of its energy when it comes into collision with another molecule.

Research on Rolling-Cut Double-Side Shear in Kinetics

2010 ◽  
Vol 145 ◽  
pp. 420-423
Author(s):  
Zhi Bing Chu ◽  
Qing Xue Huang ◽  
Li Feng Ma ◽  
Ji Dong Zhang
Keyword(s):  
Quantitative Analysis ◽  
Kinetic Model ◽  
Kinetic Theory ◽  
Kinetic Analysis ◽  
Simplified Model ◽  
Practical Application ◽  
Linkage Mechanism ◽  
New Type ◽  
Novel Method ◽  
Set Up

A simplified model based on linkage mechanism was set up through analysis of space shear mechanism and kinetic theory of new-type rolling cut double-side shear, complex and matrix has been developed for establishing the kinetic model of linkage mechanism, a novel method for quantitative analysis of rolling-cut double-side shearing was proposed and the efficiency of above mentioned method is illustrated by practical application of kinetic analysis.

The Effects of Drying Techniques on Clay-Rich Soil Texture

1974 ◽  
Vol 32 ◽  
pp. 466-467
Author(s):  
T. G. Naymik
Keyword(s):  
Critical Point ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Drying Methods ◽  
Air Drying ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Set Up ◽  
The Relationship ◽  
Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

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