Thermal Properties of Rubber Compounds. II. Heat Generation of Pigmented Rubber Compounds

1935 ◽  
Vol 8 (1) ◽  
pp. 138-149 ◽  
Author(s):  
C. E. Barnett ◽  
W. C. Mathews
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Laboratory Test ◽  
Heat Generation ◽  
The Other ◽  
Moving Plate ◽  
Rubber Compounds ◽  
Time Required ◽  
Two Machines ◽  
Rubber Block

Abstract THE first paper (1) of this series discussed thermal conductivity of rubber and a number of compounding ingredients which were measured using the electric current as the source of heat. In this article the fundamental factors controlling the generation of heat and the variations possible by pigmentation are being studied. Results obtained for pigmented rubber in the pendulum and flexometer will be discussed and correlated. In the writers' laboratory two machines have been used extensively in studying the temperature developed in rubber compounds subjected to distortion by compressive forces. The first of these is a flexometer described by Cooper (2), and the second a compression machine in which a rubber block 14 cm. (5.5 inches) in diameter and 9.53 cm. (3.75 inches) high is pounded with a definite load a specified number of times per minute. The laboratory test block used in the flexometer is in the shape of a frustrum of a rectangular pyramid, of which the base is 5.4 × 2.86 cm. (2.126 × 1.125 inches), the top 5.08 × 2.54 cm. (2 × 1 inches), and the altitude 3.81 cm. (1.5 inches). This block of rubber is compressed between two plates under definite load, one of the plates being stationary while the other travels in a circular motion of definite magnitude. After the sample has been placed in the machine, the moving plate is set to one side of the center. Both the loading and the amount of offset may be varied within wide limits. With this machine one may study either the temperature developed over a period of flexing or the time required to compress the sample a predetermined amount.

An Analysis of a Method of In-Situ Thermal Properties Determination for Geologic Formations

1985 ◽  
Vol 107 (1) ◽  
pp. 122-127
Author(s):  
J. D. Lin ◽  
T. J. Love
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Moisture Content ◽  
Oil Recovery ◽  
Thermal Methods ◽  
Core Samples ◽  
Time Required ◽  
And Storage ◽  
Flux Probe

Geothermal investigations and thermal methods of oil recovery require the thermal properties of rock be known. The thermal conductivity of rock is normally determined by measuring the properties of core samples which have been removed from the well. The major problem with this is the fact that thermal properties are dependent on the moisture content of the rock. This moisture content is very likely altered in transportation and storage. This paper presents an analysis which serves as the basis of a transient heat flux probe measurement that may be used to determine the thermal conductivity and diffusivity in situ. Such in-situ measurements would overcome the disadvantages of core samples and may also be used when core samples are not available. This analysis also provides a method of estimating the time required in order to obtain valid results. The analysis indicates rather long test times may be required for accurate results. However, it does provide a basis for evaluating the results of measurements taken for shorter times. The effects of contact thermal resistance between the probe, the well casing, and the formation are evaluated.

Thermal Properties of Si Mechanically Alloyed with FeSi2 and CrSi2

2015 ◽  
Vol 799-800 ◽  
pp. 207-211
Author(s):  
Konstantin N. Galkin ◽  
Andrey Usenko ◽  
Andrey Voronin ◽  
Dmitriy Moskovskikh ◽  
Andrey Korotitskiy ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Size Effect ◽  
Band Gap ◽  
Lattice Thermal Conductivity ◽  
Volume Fraction ◽  
Reference Sample ◽  
The Other ◽  
Mechanically Alloyed ◽  
Silicon Structures

Thermal properties of Si mechanically alloyed with FeSi2 and CrSi2 were characterized for the samples with different volume fraction of the disilicides. An anomalously low thermal conductivity observed in the FeSi2-doped samples was ascribed to an enhanced porosity of the samples which triggered the size effect on the lattice thermal conductivity reported previously for nanomeshed and “holey” silicon structures. It was also found that alloying of Si with FeSi2 led to a reduction of thermal conductivity as compared to the reference sample of pure Si prepared under the same conditions. On the other hand, alloying of Si with CrSi2 resulted in an increase in the thermal conductivity as compared to the reference sample of pure Si. The observed trends in the thermal conductivity were ascribed to the formation of impurity levels in the band gap.

Thermal Problems in Rubber Manufacture

1941 ◽  
Vol 14 (3) ◽  
pp. 683-695
Author(s):  
Stuart H. Hahn
Keyword(s):  
Thermal Properties ◽  
Heat Generation ◽  
Lower Cost ◽  
Raw Materials ◽  
Cyclic Stress ◽  
Stress Conditions ◽  
Structural Elements ◽  
Physics Laboratory ◽  
Heating And Cooling ◽  
Rubber Compounds

Abstract The threefold heat problems of the industry are, in order of their occurrence: (1) Controlled removal of heat generated in processing crude rubber. (2) Regulation of heating and cooling processes to give the most nearly uniform vulcanization in the shortest possible time. (3) Measurement and reduction of heat generation in products subject in service to cyclic stress conditions. Each of the three types of problems engages the attention of chemists and engineers as well as physicists. The chemist is constantly searching for new ingredients and combinations of materials which will promote rapid vulcanization at curing temperatures, that is, 240 to 320° F. The same rubber compounds, when unvulcanized, must be relatively insensitive to processing temperatures up to about 220° F; when vulcanized they must withstand prolonged use at temperatures above 200° F. The engineer must design curing equipment and related automatic controls. He also must design the combinations of rubber compounds and structural elements which make up the products of the industry. The physicist must measure and analyze the thermal properties of the raw materials, the rubber compounds and the finished products. He also must apply the methods of the physics laboratory to the study in the factory of thermal problems connected with production operations. The cooperation of all is essential in producing for the consumer better products at lower cost.

Effects of Thermal Conductivity of Contacting Surfaces on Point EHL Contacts

2003 ◽  
Vol 125 (4) ◽  
pp. 731-738 ◽  
Author(s):  
M. Kaneta ◽  
P. Yang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Film Thickness ◽  
Temperature Variation ◽  
Optical Interferometry ◽  
The Other ◽  
Oil Film ◽  
Entrainment Velocity ◽  
Minimum Film Thickness ◽  
Thermal Ehl

With actual and virtual materials, the effects of the thermal conductivity of contacting surfaces on EHL are investigated through experimental analyses using the optical interferometry technique and the Newtonian thermal EHL analyses in consideration of the variation of oil properties in all directions within the film. A mineral bright stock is used as a lubricant. It is found that the distributions of pressure and film thickness, including the minimum film thickness, are influenced very much by the entrainment velocity and the slide-roll ratio. One of the causes is the temperature-viscosity wedge action produced by the temperature variation across the oil film, and the other is an increase in oil temperature at the entrance of the contact due to the heat produced by the compression work and the shearing of the oil. The degree of both influences depends on the thermal properties of contacting materials.

COOLING RATES OF FOODS

1973 ◽  
Vol 36 (3) ◽  
pp. 167-171 ◽  
Author(s):  
R. W. Dickerson ◽  
R. B. Read
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Food Sample ◽  
Cooling Rates ◽  
Rapid Cooling ◽  
Low Thermal Conductivity ◽  
Time Required ◽  
Plastic Containers ◽  
White Sauce

Rapid cooling is essential to prevent multiplication of microorganisms in potentially hazardous foods. This requirement is frequently not met with viscous foods in large containers. The time required to cool an 8-gal container of white sauce from 105 to 57 F was 25 hr. Similarly, a 14-gal container of beef stew required 84 hr to cool from 115 to 50 F. Under some conditions, cooling times are directly proportional to the square of the shortest dimension of the food sample. For example, if the shortest dimension is doubled, cooling times are increased by a factor of four. The effect of most plastic containers on cooling rates of foods is generally insignificant. Thermal properties of polyethylene, nylon, and Teflon are similar to thermal properties of foods, and a 1/8-inch-thick container will have about the same effect as an additional 1/8-inch thickness of the food. Polystyrene, however, has a very low thermal conductivity and will significantly delay cooling of most foods.

Correlation of Electronic and Thermal Properties of Short Channel nMOSFETS

1999 ◽  
Author(s):  
M. Palaniappan ◽  
V. Ng ◽  
R. Heiderhoff ◽  
J.C.H. Phang ◽  
G.B.M. Fiege ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Hot Spots ◽  
Light Emission ◽  
Photon Emission ◽  
Thermal Image ◽  
Short Channel ◽  
Physical Phenomena ◽  
Backside Illuminated

Abstract Light emission and heat generation of Si devices have become important in understanding physical phenomena in device degradation and breakdown mechanisms. This paper correlates the photon emission with the temperature distribution of a short channel nMOSFET. Investigations have been carried out to localize and characterize the hot spots using a spectroscopic photon emission microscope and a scanning thermal microscope. Frontside investigations have been carried out and are compared and discussed with backside investigations. A method has been developed to register the backside thermal image with the backside illuminated image.

Maximizing Heat Transfer Through Joint Fin Systems

2005 ◽  
Vol 128 (2) ◽  
pp. 203-206 ◽  
Author(s):  
A.-R. A. Khaled
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Performance ◽  
Critical Length ◽  
The Other ◽  
Rigid Fixation ◽  
Convection Coefficient ◽  
Heat Transfer Characteristics ◽  
Cold Side ◽  
Transfer Characteristics

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.

Sign in / Sign up

Export Citation Format

Share Document