An Improved Low-Temperature Brittleness Test

1949 ◽  
Vol 22 (3) ◽  
pp. 820-827 ◽  
Author(s):  
E. F. Smith ◽  
G. J. Dienes
Keyword(s):  
Low Temperature ◽  
Temperature Interval ◽  
Statistical Study ◽  
Distribution Curve ◽  
Simple Analysis ◽  
Reasonable Amount ◽  
Brittle Point

Abstract An improved low-temperature brittleness tester, capable of testing five specimens simultaneously, is described. All machine specifications conform to A.S.T.M. Method D 746-44T. Data are presented which show that many elastomers do not possess a sharp brittle point but are characterized by a distribution of failures over a temperature interval. The improved brittleness tester makes it possible to carry out the necessary statistical study of the distribution of per cent failures versus temperature with a reasonable amount of work. A simple analysis of the resulting distribution curve is presented.

Effect of Low Temperatures on Young's Modulus of Elastomers

1944 ◽  
Vol 17 (2) ◽  
pp. 421-434
Author(s):  
John W. Liska
Keyword(s):  
Low Temperature ◽  
Natural Rubber ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Operating Temperature ◽  
Temperature Curve ◽  
Simple Test ◽  
Successful Operation ◽  
Brittle Point ◽  
Base Polymer

Abstract The data presented should be of value to the rubber technologist who may be called on to produce a compound having a given base polymer capable of performing satisfactorily down to a specified low temperature. Although natural rubber is basically more cold-resistant than some of the other synthetic elastomers, it has been found possible to add larger quantities of softeners and modifiers to the latter (without causing too serious a decrease in mechanical properties) than can be added to natural rubber. Consequently, it is possible to compound synthetic elastomer stocks having better low-temperature properties than natural rubber stocks. In the case of material which does not exhibit crystallization, it should be possible (either from experience or by a simple test at normal temperatures) to set an upper limit for the Young's modulus of the proposed stock consistent with satisfactory operation. A modulus vs. temperature curve of the stock would then indicate definitely whether the observed modulus at the specified low temperature exceeded the limit previously set. If it did not and, in addition, the brittle-point temperature was found to be below the specified operating temperature, successful operation could reasonably be expected. In general, it is not necessary to calculate Young's modulus in all cases. For a given load and sample size, the deflection as measured would serve equally well as an index.

ELECTRICAL CONDUCTIVITY OF SEVERAL SAMPLES OF OLIVINITES, PERIDOTITES, AND DUNITES, AS A FUNCTION OF PRESSURE AND TEMPERATURE

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Z. Dvořák
Keyword(s):  
Electrical Conductivity ◽  
Low Temperature ◽  
Temperature Interval ◽  
Geomagnetic Variation ◽  
Conductivity Data ◽  
Exponential Term ◽  
Temperature Range ◽  
The Earth ◽  
Straight Line ◽  
Temperature Side

The electrical conductivity σ of several samples of olivinites, peridotites, and dunites was measured in the temperature range between 250 and 700°C under quasi‐hydrostatic pressures from 1 to 20 kb. Using a straight line extrapolation of logσ values taken at pressures greater than 6–8 kb, graphs of logσ versus [Formula: see text] were plotted for 0 and 20 kb. These graphs exhibit similar general features to those obtained under room pressure by other authors, but they appear to be shifted towards the low temperature side. This shift may be explained plausibly by assuming much higher values of the preexponential term but only minor variations of the exponential term in the expression [Formula: see text] exp ([Formula: see text]). The electrical conductivity of the samples with high percentage of serpentinized olivine (more than 35 percent) is characterized by a decrease of σ in the temperature interval between 470 and 625°C and is related to the content of serpentine in the samples and its dehydration in this temperature range. Some estimates of temperature within the earth based on conductivity data inferred from magnetotelluric and geomagnetic variation methods are discussed in terms of the present results which suggest substantially lower values of T to be attained at a particular depth. Also, an attempt is made to reexamine assumptions involving the theoretically deduced equation of the electrical conductivity within the earth.

scholarly journals Improvement of Low-Temperature Performance of Buton Rock Asphalt Composite Modified Asphalt by Adding Styrene-Butadiene Rubber

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2358 ◽  
Author(s):  
Xiyan Fan ◽  
Weiwei Lu ◽  
Songtao Lv ◽  
Fangwei He
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Stiffness Modulus ◽  
Modified Asphalt ◽  
Temperature Performance ◽  
Brittle Point ◽  
Low Temperature Performance ◽  
Styrene Butadiene

To improve the low-temperature performance of the Buton rock asphalt (BRA)-modified asphalt, styrene-butadiene rubber (SBR) was added to it. The BRA-modified asphalt and SBR-BRA composite modified asphalt were prepared by high-speed shearing method. The penetration, softening point, ductility, and Brookfield viscosity of the two kinds of asphalt were measured. The dynamic shear rheometer (DSR) and the beam bending rheometer (BBR) were employed to research the performance of BRA-modified asphalt by adding SBR. The results showed that the pure asphalt in BRA was the main reason to reduce the low-temperature performance of neat asphalt when the content of BRA was 19%. However, the ash in BRA was the main factor to reduce the low-temperature performance when its content was more than 39.8%. When the BRA content was 59.8%, the SBR-BRA composite modified asphalt with SBR contents of 2%, 4%, 6%, and 8%, and it shows that the penetration and ductility of the BRA-modified asphalt are increased by the addition of SBR. The equivalent brittle point was reduced, the stiffness modulus was decreased, and the creep rate was increased. At the same time, the Brookfield viscosity was reduced and the rutting factor was increased. The stiffness modulus of the SBR-BRA composite modified asphalt mixture was increased. That is to say, when SBR was mixed into the BRA-modified asphalt, the low-temperature performance could be remarkably improved based on ensuring high-temperature performance. The low-temperature index of composite modified asphalt was analyzed. It was recommended to apply the equivalent brittle point to evaluate the low-temperature performance of SBR-BRA composite modified asphalt.

Low-temperature structure of rubrene single crystals grown by vapor transport

2006 ◽  
Vol 62 (2) ◽  
pp. 330-334 ◽  
Author(s):  
Oana D. Jurchescu ◽  
Auke Meetsma ◽  
Thomas T. M. Palstra
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Single Crystals ◽  
Temperature Interval ◽  
Open System ◽  
Vapor Transport ◽  
Entire Temperature Range ◽  
Physical Vapor Transport ◽  
Temperature Structure ◽  
Temperature Range

We report the crystal structure of rubrene, C42H28 (5,6,11,12-tetraphenyltetracene), in the temperature interval 100–300 K. The crystals are grown by physical vapor transport in an open system. The crystal structure is orthorhombic over the entire temperature range.

Evaluating Low-Temperature Stiffness and Brittle Point in Elastomers

1944 ◽  
Vol 17 (1) ◽  
pp. 107-115
Author(s):  
Floyd L. Graves ◽  
Arnold R. Davis
Keyword(s):  
Low Temperature ◽  
Test Methods ◽  
Brittle Point ◽  
The Times ◽  
Method Of Evaluation

Abstract The illustrations indicate some of the possibilities in our method of evaluation. The urgency of the times requires that all workers come forward with any new test methods that may be of value in developing better compounds, without consuming valuable time investigating all of the possibilities and limitations of such methods. Possibly other workers will wish to apply the methods described, in their studies on the effects of plasticizers, curing times and temperatures, reenforcing fillers, etc., in low-temperature compounding of the various new elastomers being pressed into service today.

scholarly journals Design and fabrication of sintered Nd-Fe-B magnets with a low temperature coefficient of intrinsic coercivity

2009 ◽  
Vol 41 (1) ◽  
pp. 91-99 ◽  
Author(s):  
X.G. Cui ◽  
M. Yan ◽  
T.Y. Ma ◽  
W. Luo ◽  
S.J. Tu
Keyword(s):  
Low Temperature ◽  
Temperature Coefficient ◽  
Influencing Factors ◽  
Temperature Interval ◽  
Magnetocrystalline Anisotropy ◽  
Anisotropy Field ◽  
Absolute Value ◽  
Temperature Coefficients ◽  
Intrinsic Coercivity ◽  
The Absolute

To decrease the temperature coefficients of sintered Nd-Fe-B magnets, the influencing factors on temperature coefficients, especially the reversible temperature coefficient ? of intrinsic coercivity Hcj, were analyzed. The results showed that the absolute value of ? decreased with increasing Hcj and also the ratio of microstructure parameter c to Neff, indicating that the increase of magnetocrystalline anisotropy field HA and c/Neff can effectively decrease the absolute value of ?. On the basis of this analysis, a sintered Nd-Fe-B magnet with a low temperature coefficient of Hcj was fabricated through composition design, and the value of ? was only -0.385%/?C in the temperature interval of 20-150?C.

An Improved Brittle Point Apparatus

1946 ◽  
Vol 19 (3) ◽  
pp. 844-847
Author(s):  
F. L. Graves
Keyword(s):  
Low Temperature ◽  
Brittle Point

Abstract In the paper “Evaluating Low Temperature Stiffness and Brittle Point in Elastomers” several methods for determining the brittle points of rubber and rubberlike compounds were reviewed, and the apparatus developed in these laboratories in 1942 for this test was described in detail.

Research on Enzymatic Hydrolysis Lignin Modified Petroleum Asphalt

2011 ◽  
Vol 306-307 ◽  
pp. 1080-1083 ◽  
Author(s):  
Zhi Dong Zhao ◽  
Yao Xie ◽  
Xian Su Cheng ◽  
Yan Qiao Jin ◽  
Ming Yang Xu
Keyword(s):  
Enzymatic Hydrolysis ◽  
Low Temperature ◽  
Physical Properties ◽  
Softening Point ◽  
Hydrolysis Lignin ◽  
Petroleum Asphalt ◽  
Modified Asphalt ◽  
Penetration Index ◽  
Temperature Performance ◽  
Brittle Point

In this paper, a series of enzymatic hydrolysis lignin modified petroleum asphalts were prepared. The physical properties such as softening point, ductility at low temperature and penetration of the modified asphalt were investigated. The penetration index of asphalt modified with EHL was higher than that of unmodified asphalt, equivalent softening point increased and equivalent brittle point decreased with the increase of EHL amount, which showed that the addition of EHL was favorable to reduce the temperature susceptivity of asphalt. When the EHL was 4%, the ductility was 39.0 cm. Meanwhile, low temperature performance of asphalt could be further improved by adding EHL and a small amount of SBS.

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