Heat Conductivity of Rubber at Low Temperatures

1940 ◽  
Vol 13 (4) ◽  
pp. 830-830
Author(s):  
Adolf Schallamach
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Temperature Region ◽  
Heat Conductivity ◽  
Low Temperatures ◽  
Room Temperature ◽  
Tire Rubber ◽  
Order Of Magnitude ◽  
Temperature Work

Abstract While examining the possibilities of applying rubber in low temperature work, we were hampered by the lack of available data on its physical properties at low temperatures. We were aware of the difficulties to be expected in making accurate measurements in that temperature region, and this applied especially to the heat conductivity, in which we were particularly interested. To obtain at least an estimate of the order of magnitude, we carried out some measurements of the heat conductivity of commercial rubber (North British tire rubber) at room temperature and at the temperature of liquid air.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

CERROCAST Alloy

Alloy Digest ◽  
1980 ◽  
Vol 29 (3) ◽  
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Eutectic Alloy ◽  
Heat Treating ◽  
Melting Range ◽  
Spray Painting ◽  
Metal Products ◽  
Temperature Work

Abstract CERROCAST Alloy is a non-eutectic alloy with a melting range from 281 F to 338 F. It provides manufacturing engineers with an easily castable material that is ready for use soon after it freezes; moreover, it can be recovered readily and recycled into new uses any number of times. Cerrocast alloy is used widely for spray molding techniques, for sealing and soldering in low-temperature work, for proof casting in foundries and for masks in spray painting and electroplating. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on heat treating, machining, and joining. Filing Code: Sn-9. Producer or source: Cerro Metal Products.

scholarly journals The behaviour of visual purple at low temperature

1941 ◽  
Vol 179 (977) ◽  
pp. 151-159 ◽  
Keyword(s):  
Aqueous Solution ◽  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Absorption Curve ◽  
Quantum Yields

Visual purple is soluble and stable in a mixture of glycerol and water (3:1). At room temperature the spectrum of such a solution is identical with that of the aqueous solution. At — 73° C the peak of the absorption curve is higher and narrower than at room temperature, and it is shifted towards longer waves. The product of photodecomposition at — 73° C has a spectrum in ­ dependent of pH and is at low temperatures thermostable and photostable, but at room temperature it decomposes therm ally to indicator yellow. The primary product appears to be identical with transient orange. The quantum yields of the photoreaction at low and at room temperature are of the same order.

Compressive Plasticity of Zr-Based Bulk Metallic Glass at Low Temperature

2012 ◽  
Vol 443-444 ◽  
pp. 583-586
Author(s):  
Ya Juan Sun ◽  
Ri Ga Wu ◽  
Hong Jing Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Low Temperatures ◽  
Room Temperature ◽  
Shear Bands ◽  
Strain Curve ◽  
Testing Temperature ◽  
Stress Strain Curve

The mechanical properties of a new Zr-based bulk metallic glass at low temperatures were investigated. The results indicate that the fracture strength increases significantly (4.9%) and the global plasticity increases somewhat when testing temperature is lowered to 123K. The stress-strain curve of the sample deformed exhibits more serrations and smaller stress drop due to formation of more shear bands at low temperature than at room temperature.

Electrical Properties of Heavily Be-doped GaAs grown by Molecular Beam Epitaxy

1989 ◽  
Vol 163 ◽  
Author(s):  
H. Shibata ◽  
Y. Makita ◽  
A. Yamada ◽  
N. Ohnishi ◽  
M. Mori ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Carrier Concentration ◽  
Valence Band ◽  
Temperature Region ◽  
Room Temperature ◽  
Molecular Beam ◽  
Impurity Band ◽  
Carrier Scattering

AbstractElectrical properties of heavily Be-doped GaAs grown by molecular beam epitaxy were investigated systematically in a wide range of Be-concentration from 1× 1014 up to 2× 1020 cm-3 by using yan der Pauw technique. Probable carrier scattering mechanisms observed in this work are discussed by taking into account the radiative mechanisms of several new photoluminescence emissions previously observed in the band-edge-emission region of the samples. All samples were checked their electrical properties first at room-temperature. Five selected samples out of them were measured from 10° K up to room-temperature. Samples having the carrier concentration from 1014 to 1018 cm3 presented typical semiconductor-like conduction with finite carrier excitation energy. For samples having carrier concentration 7× 1016 cm -3, the conduction mechanism at high temperature region above 30β K was dominated by holes thermally excited into valence band. At low temperature region below 30° K . it was dominated by holes hopping from neutral to ionized acceptors with the assistance of phonons. Hole mobilities of samples having the carrier concentration from 1017 to 1018 cm-3 showed an anomalous behavior in the low temperature region, which suggests the presence of a new type of carrier scattering mechanism. A radiative center denoted by lg-gl observed in this concentration region will be a candidate scattering center to explain these electrical behaviors. Samples having the carrier concentration larger than 1019 cm-3 demonstrated typically metallic electric conduction not owing to thermally excited carriers, which means that an impurity band is formed but merged with valence band. The density of state of this combined valence band mixed with impurity band can be supposed to reflect carrier concentration dependence of the PL emission bands observed in this region, i.e. [g-g]α , [g-g]β and [g-g]γ .

scholarly journals THE INFLUENCE OF TEMPERATURE ON THE ACTION OF STRYCHNIN IN FROGS

1913 ◽  
Vol 18 (3) ◽  
pp. 300-309 ◽  
Author(s):  
Thomas Stotesbury Githens
Keyword(s):  
Low Temperature ◽  
High Temperatures ◽  
Low Temperatures ◽  
Room Temperature ◽  
Drug Action ◽  
The State ◽  
Great Caution ◽  
Influence Of Temperature ◽  
Influence Of Temperature On

In order to establish the influence of temperature upon the effect of varying doses of strychnin injected into frogs, the animals must be kept under observation for several days and at various definite degrees of temperature. Statements that the animal was kept "cold," "at room temperature," or "warm" are insufficient. With a certain dose tetanus may result constantly at 30° C. yet never appear at 21° C., and either of these temperatures might be described as warm, when compared to a room temperature of 15° C. Furthermore an animal may apparently fail to respond in the cold to an injection of certain doses of strychnin and yet be found in tetanic convulsions the next day. That an animal may have late, long lasting, or strong tetanus while kept at such a low temperature as 5° C. after an injection of a dose of strychnin smaller than 0.01 of a milligram per frog emphasizes the fact that great caution must be exercised in formulating laws as to the influence of temperature on drug action. The main results of this investigation may be summarized as follows: Doses of strychnin amounting to 0.0006 of a milligram per gram of frog will cause tetanus at all temperatures between 5° C. and 30° C., although at low temperatures the tetanus may appear late. A dose of 0.0003 of a milligram per gram of frog will frequently produce tetanus at 5° C. as well as at 30° or 27° C., but may nevertheless fail to produce any reaction at such an intermediary temperature as 21° C. Smaller doses, 0.0002 of a milligram per gram, will cause tetanus in the cold but not at high temperatures. It may be stated in general that in frogs kept at low temperatures the tetanic state sets in later, continues longer, and each tetanic attack is of longer duration, while in the interval between the attacks the state of tonus is higher and the animals are more irritable than when they are kept at higher temperatures.

INVESTIGATIONS OF PERMEABILITY, DIAPAUSE, AND HATCHING IN THE EGGS OF THE MOSQUITO AEDES HEXODONTUS DYAR

1958 ◽  
Vol 36 (4) ◽  
pp. 541-554 ◽  
Author(s):  
W. E. Beckel
Keyword(s):  
Low Temperature ◽  
Sodium Hypochlorite ◽  
Water Loss ◽  
Low Temperatures ◽  
Room Temperature ◽  
Early Embryo ◽  
Adult Mosquito ◽  
Egg Cell ◽  
Distilled Water ◽  
Exposure To Cold

Methods for collection in the laboratory of many thousands of eggs from field-collected, blood-fed females are described. Also a way of separating fertile from infertile eggs is outlined. When the eggs are laid they are white but begin to darken within one-half hour. The darkening did not occur when the egg cell or early embryo was killed.Two changes in permeability in the prediapause stage of the eggs of Aedcs hexodontus were observed. The first took place as the chorion changed from white to black. The egg lost and gained water easily when first laid but resisted water loss and uptake as the chorion darkened. However, a complete waterproofing did not result. With the formation of the transparent cuticle a further change in permeability occurred. The egg lost hardly any water even when exposed to extreme desiccation and what little water was lost was regained very slowly. However, the cuticle, with the chorion removed in sodium hypochlorite, was quite permeable. The impermeability of the chorion and cuticle combination must result from the bonding between the two and this bonding must be disrupted by the dechorionation.To study the obligate diapause that occurs in the late embryogeny of the mosquito egg the effect of making water available to the embryo, of light, and of low temperature was studied. Diapause was not broken when water was available to the embryo, nor did alternate periods of light and dark at room temperature or at lower temperatures disrupt the diapause. To test the influence of cold the temperature of 1° and −3 °C. were used to simulate the temperatures in the field. The low temperatures were found to terminate the diapause but the numbers of eggs hatching did not steadily increase with an increase in the time of exposure to cold. No clue has as yet been discovered to explain these results. A hatching infusion of decaying adult mosquito bodies in distilled water was found to give more hatching than did distilled water alone. The mechanism of the hatching stimulus is not known.

Biofuel Compatibility of Sealing Materials at Low Temperatures

2017 ◽  
Vol 44 (11) ◽  
pp. 1-4
Author(s):  
H.-C. Rost
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Automotive Industry ◽  
Low Temperatures ◽  
Regulatory Framework ◽  
New Markets ◽  
New Developments ◽  
Compression Set ◽  
Sealing Performance ◽  
Sealing Materials

The combination of very good biofuel compatibility with excellent low-temperature properties is of major importance to the automotive industry. Changes in the regulatory framework and the tapping of new markets have increasingly led to new developments in this field. Parker has developed FKM compounds with TR10 values of −30°C, −35°C, −40°C and −45°C, which display only slight changes in physical properties upon storage in FAM B, E85 and KGS (VW first fill fuel). The sealing performance of these compounds at very low temperatures was investigated in compression set tests from −25°C down to −50°C.

A Study of Stiffness Testing of Elastomers at Low Temperatures

1955 ◽  
Vol 28 (1) ◽  
pp. 335-347
Author(s):  
F. S. Conant
Keyword(s):  
Low Temperature ◽  
Temperature Region ◽  
Low Temperatures ◽  
Temperature Limit ◽  
Test Methods ◽  
Beam Method ◽  
Stiff Material ◽  
Rubberlike Materials ◽  
Good Agreement

Abstract In light of the above discussion, it does not appear logical to choose a “best” test for determining low-temperature moduli. A study of the data as a whole indicates that the correlation between the two sets of values from the simple beam-method (laboratories C-1 and C-2) are closest, but there is nothing to show that they are the most valid. It should be emphasized that, in the temperature region of greatest technical importance, that is, where the rubber is changing from its ordinary flexible state to a hard stiff material, the different tests show good agreement. A low-temperature limit of serviceability would be close to −80° F for the Hevea gum and −60° F for the GR-S by each of the methods studied. Another conclusion that might well be reached by a study of the test methods and data presented is that the term “modulus”, as applied to rubberlike materials, is rather vague unless the method of obtaining that modulus is also given.

Electrical resistivity measurements in palladium–hydrogen alloys

1968 ◽  
Vol 46 (18) ◽  
pp. 2065-2071 ◽  
Author(s):  
C. T. Haywood ◽  
L. Verdini
Keyword(s):  
Electrical Resistivity ◽  
Transition Metals ◽  
Low Temperatures ◽  
Room Temperature ◽  
Residual Resistivity ◽  
Resistivity Measurements ◽  
Order Of Magnitude ◽  
Rate Of Cooling ◽  
High Concentrations ◽  
Pure Palladium

The resistivity of palladium and palladium–hydrogen alloys has been studied in the temperature range 2–300 °K. At low temperatures (10 °K < T < 60 °K), it is found that ρ1 is proportional to Tn with n = 3.1 for pure palladium; but n decreases to 2.3 for an alloy with H/Pd = 0.25. For high concentrations and at low temperatures, the resistivity is found to be dependent upon the time and rate of cooling through the [Formula: see text] transformation. The residual resistivity is lower for faster cooling rates.The increase in resistivity due to 1 at. % hydrogen in palladium is calculated and found to be of the same order of magnitude as that for interstitials in other f.c.c. metals, but less then that found for hydrogen in the b.c.c. transition metals tantalum and niobium at room temperature.

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