Brittle Points of Natural and Synthetic Rubber Stocks

1944 ◽  
Vol 17 (1) ◽  
pp. 92-99
Author(s):  
Ross E. Morris ◽  
Robert R. James ◽  
Theodore A. Werkenthin
Keyword(s):  
Low Temperatures ◽  
Cold Resistance ◽  
Practical Significance ◽  
Synthetic Rubber ◽  
Point Test ◽  
Brittle Point ◽  
Lower Temperature ◽  
Natural And Synthetic

Abstract The slow-bend brittle point test does not have the same practical significance as the Bell Telephone Laboratories brittle point test because most rubber articles which are exposed to low temperatures in service are required to withstand fairly rapid flexing. If the slow-bend brittle point test were used as a criterion of the cold resistance of these rubber articles, it might qualify the rubbers for a lower temperature than they could safely withstand in service. The brittle point test developed by the Bell Telephone Laboratories is simple and sensitive. It is believed that this test may advantageously be used to study all cold resistance problems where damage to the rubber itself and not increase in stiffness is the first consideration.

Effect of Storage and Temperature on Flexibility of Natural and Synthetic Rubbers

1948 ◽  
Vol 21 (4) ◽  
pp. 864-876
Author(s):  
John B. Gregory ◽  
Irving Pockel ◽  
John F. Stiff
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Strain Curve ◽  
Polymer Chains ◽  
Stress Strain Curve ◽  
Low Temperature Storage ◽  
Synthetic Rubber ◽  
Loading And Unloading ◽  
Temperature Storage ◽  
Natural And Synthetic

Abstract A new method for measuring the flexibility of rubber has been described. The method consists essentially in determining the stress-strain curve obtained by loading and unloading a loop formed from a one-inch by six-inch strip cut from a test slab. A coefficient of flexibility independent of the thickness of the sample and, in addition, information on per cent resilience were obtained. By the use of the method described, the behavior of various natural and synthetic rubber gas mask facepiece compounds was studied during one month to three months' exposure at various temperatures down to −20° F. Progressive stiffening probably due to crystallization was found for natural rubber, GR-I, and GR-M compounds at low temperatures. No tendency to crystallize was noted for the GR-S compound. Of the crystallizable polymers GR-I was the most resistant, and GR-M the least resistant to stiffening during low temperature storage. It is of course evident that different polymers have inherently different degrees of resistance to low temperatures. Disregarding these inherent differences the work reported indicates that the resistance of elastomer compounds to stiffening during prolonged low temperature storage is favored by the following: 1. Use of interpolymers made from monomer mixtures having a relatively large proportion of each component, thus obtaining mutual intereference with crystallization. 2. Use of a “tight” cure which probably so impedes the movement of the polymer chains as to make crystallization difficult.

Brittle Point of Rubber on Freezing

1942 ◽  
Vol 15 (2) ◽  
pp. 243-250
Author(s):  
M. L. Selker ◽  
G. G. Winspear ◽  
A. R. Kemp
Keyword(s):  
Low Temperatures ◽  
High Rate ◽  
Simple Method ◽  
Vulcanized Rubber ◽  
Synthetic Rubber ◽  
Brittle Point ◽  
New Material ◽  
Point Data ◽  
First Time

Abstract The need for a simple method of determining brittle points which would be adaptable to a large number of materials led the writers to develop the apparatus described below. There is presented here, for the first time, brittle point data on certain natural and synthetic rubber compositions. The study of the variation with temperature of the mechanical properties of elastomers is of immediate practical and theoretical interest. Recently Kistler attempted a correlation of temperature-strength data of polymers with their chemical structure. On the other hand, the increasing use of synthetic high polymers at low temperatures for insulation and mechanical purposes requires a more complete knowledge of their behavior under conditions of extreme cold. The determination of the brittle point offers a simple method for investigating the possible use of a new material at low temperatures. In 1928 Kohman and Peek described a method whereby a small strip of material at a known temperature was bent quickly through 90° by a hammer blow. They found that within rather wide limits the brittle temperature was independent of the sample dimensions and bending angle, but that a high rate of deformation was necessary for reproducible results. The brittle point was found to be definite and reproducible within ±2° C for the materials studied. Using this method, Kemp determined the brittle point range of crude and vulcanized rubber, balata, guttapercha, and paragutta.

Research of the cold resistance of metals by indentation with registration of an acoustic emission signal

2020 ◽  
pp. 61-64
Author(s):  
Yu.G. Kabaldin ◽  
A.A. Khlybov ◽  
M.S. Anosov ◽  
D.A. Shatagin
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Acoustic Emission ◽  
Acoustic Emission Signal ◽  
Low Temperatures ◽  
Cold Resistance ◽  
Emission Signal ◽  
Impact Bending ◽  
Artificial Neural

The study of metals in impact bending and indentation is considered. A bench is developed for assessing the character of failure on the example of 45 steel at low temperatures using the classification of acoustic emission signal pulses and a trained artificial neural network. The results of fractographic studies of samples on impact bending correlate well with the results of pulse recognition in the acoustic emission signal. Keywords acoustic emission, classification, artificial neural network, low temperature, character of failure, hardness. [email protected]

scholarly journals Alternative of bone china and porcelain as ceramic hand molds for rubber latex glove films formation via dipping process

2020 ◽  
Vol 59 (1) ◽  
pp. 523-537
Author(s):  
Chaturaphat Tharasana ◽  
Aniruj Wongaunjai ◽  
Puwitoo Sornsanee ◽  
Vichasharn Jitprarop ◽  
Nuchnapa Tangboriboon
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Mold Surface ◽  
Rubber Latex ◽  
Latex Glove ◽  
Bone China ◽  
Synthetic Rubber ◽  
Natural And Synthetic

AbstractIn general, the main compositions of porcelain and bone china composed of 54-65%wt silica (SiO2), 23-34% wt alumina (Al2O3) and 0.2-0.7%wt calcium oxide (CaO) suitable for preparation high quality ceramic products such as soft-hard porcelain products for teeth and bones, bioceramics, IC substrate and magneto-optoelectroceramics. The quality of ceramic hand mold is depended on raw material and its properties (pH, ionic strength, solid-liquid surface tension, particle size distribution, specific surface area, porosity, density, microstructure, weight ratio between solid and water, drying time, and firing temperatures). The suitable firing conditions for porcelain and bone china hand-mold preparation were firing at 1270°C for 10 h which resulted in superior working molds for making latex films from natural and synthetic rubber. The obtained fired porcelain hand molds at 1270°C for 10 h provided good chemical durability (10%NaOH, 5%HCl and 10%wtNaCl), low thermal expansion coefficient (5.8570 × 10−6 (°C−1)), good compressive (179.40 MPa) and good flexural strength (86 MPa). While thermal expansion coefficient, compressive and flexural strength of obtained fired bone china hand molds are equal to 6.9230 × 10−6 (°C−1), 128.40 and 73.70 MPa, respectively, good acid-base-salt resistance, a smooth mold surface, and easy hand mold fabrication. Both obtained porcelain and bone china hand molds are a low production cost, making them suitable for natural and synthetic rubber latex glove formation.

Natural and Synthetic Rubber. IV. 4-Methyl-4-Octene by Isoprene Ethylation

1930 ◽  
Vol 3 (3) ◽  
pp. 483-484
Author(s):  
Thomas Midgley ◽  
Albert L. Henne
Keyword(s):  
Double Bond ◽  
Synthetic Rubber ◽  
Double Bond System ◽  
Bond System ◽  
Usual Behavior ◽  
Natural And Synthetic ◽  
Long Chains

Abstract Isoprene has been ethylated; 4-methyl-4-octene was formed exclusively. The structure of this nonene is in agreement with the usual behavior of a conjugated double bond system. This type of addition is further evidence in favor of the hypothesis which regards the polymerization of isoprene to synthetic rubber as the formation of long chains of isoprene units linked together- by ordinary valences in the 1,4-position.

NATURAL AND SYNTHETIC RUBBER. XI. CONSTITUENTS OF THE MILLED RUBBER HYDROCARBON

1932 ◽  
Vol 54 (8) ◽  
pp. 3381-3383 ◽  
Author(s):  
Thomas Midgley ◽  
Albert L. Henne ◽  
Mary W. Renoll
Keyword(s):  
Synthetic Rubber ◽  
Natural And Synthetic

Study of the low cycle fatigue of 12Cr18Ni10Ti steel based on fractal analysis and artificial intelligence approaches

2021 ◽  
Vol 87 (9) ◽  
pp. 59-67
Author(s):  
A. A. Khlybov ◽  
Yu. G. Kabaldin ◽  
M. S. Anosov ◽  
D. A. Ryabov ◽  
D. A. Shatagin
Keyword(s):  
Neural Network ◽  
Growth Rate ◽  
Fractal Dimension ◽  
Low Temperatures ◽  
Main Crack ◽  
Fatigue Loading ◽  
Wide Range ◽  
Lower Temperature ◽  
Number Of Cycles ◽  
Dimension Index

The evolution of the structure and assessment of the age limit of steel 12Cr18Ni10Ti upon fatigue loading is considered using neural network modeling and approaches of fractal analysis of the microstructure. An algorithm for processing images of the microstructures has been developed to improve their quality. An indicator of the fractal dimension of the image is used as a quantitative indicator for assessing the evolution of the microstructure of the surface metal layer. A quantitative assessment of the structures at different stress amplitudes is carried out in a wide range of low temperatures using the fractal dimension index. Correlation of the fractal dimension index with the run of the sample material is shown. The appearance of the main crack was observed in the range of 0.7 - 0.8 from the number of cycles to failure, after which the crack growth rate increased. At a lower temperature, the main crack is formed later, but further loading results in a higher crack growth rate. Formation of the secondary phases in austenitic steel at a lower temperature occurred at earlier stages than that at a temperature of t = +20°C, which led to hardening of the material. An artificial neural network (ANN) has been developed and trained for assessing structural changes in metal proceeding from the fractal dimensionality of the microstructure images at different stages of fatigue loading. The developed neural network made it possible to estimate with a sufficiently high accuracy the number of cycles before damage of the sample and the residual life of the material. Thus, the developed ANN can be used to assess the current state of the material in a wide range of low temperatures.

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