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.

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.

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.

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.

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.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast

1988 ◽  
Vol 46 ◽  
pp. 256-257
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Eugene L. Vigil
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Standard Specimen ◽  
High Vacuum ◽  
Specimen Holder ◽  
Sputter Coating ◽  
Fresh Frozen ◽  
Gain Access ◽  
Scanning Electron ◽  
Transfer Device

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.

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