The Nature of Structural Changes of Butadiene Rubbers Caused by High Temperatures (100–200° C)

1952 ◽  
Vol 25 (1) ◽  
pp. 33-35 ◽  
Author(s):  
A. S. Kuzminskii˘ ◽  
I. A. Shokhin ◽  
R. M. Belitzkaya
Keyword(s):  
Tensile Strength ◽  
Thermal Effect ◽  
High Temperatures ◽  
Structural Changes ◽  
Temperature Range ◽  
The Subject ◽  
Mechanism Of Oxidation

Abstract In theories developed by Kuzminskii˘ and his collaborators concerning the mechanism of oxidation of rubbers, the question of a direct thermal effect on their structure was not discussed. Nevertheless, with certain rubbers, structural changes which are caused by high temperatures play a very important part in the total complex of structural changes undergone by these rubbers during processing and, after vulcanization, by their products during service. Dogadkin, Zayonchkovskii˘, Zayonchkovskaya, Pisarenko, and Astafyez, Kuzminskii˘, Shanin, Degteva, Lapteva, and other Soviet investigators have shown that, when butadiene rubbers are heated in the temperature range of 100–200° C, structural changes take place which are characterized by increases of tensile strength and modulus, decrease of extensibility, decrease of unsaturation, etc. The question of the causes of such extensive changes in rubber is the subject of this discussion. Rebinder has proven unsubstantiated the reasoning of several investigators regarding these processes, and has shown the necessity of carrying out direct experiments which would provide an explanation of their nature.

scholarly journals The combustion of aromatic and alicyclic hydrocarbons. II. The ignition of aromatic hydrocarbons at high temperatures

1939 ◽  
Vol 171 (946) ◽  
pp. 421-433 ◽  
Keyword(s):  
High Temperatures ◽  
Aromatic Hydrocarbons ◽  
Isothermal Oxidation ◽  
Present Communication ◽  
Temperature Range ◽  
Benzene Toluene ◽  
The Subject ◽  
Kinetics Of

In the first paper of this series (Burgoyne 1937) the kinetics of the isothermal oxidation above 400° C of several aromatic hydrocarbons was studied. The present communication extends this work to include the phenomena of ignition in the same temperature range, whilst the corresponding reactions below 400° C form the subject of further investigations now in progress. The hydrocarbons at present under consideration are benzene, toluene, ethylbenzene, n -propylbenzene, o-, m - and p -xylenes and mesitylene.

scholarly journals Pt-Rh Alloys: Investigation Of Tensile Strength And Elongation At High Temperatures

2015 ◽  
Vol 60 (2) ◽  
pp. 643-647
Author(s):  
B. Trumić ◽  
L. Gomidželović ◽  
S. Marjanović ◽  
V. Krstić ◽  
A. Ivanović ◽  
...  
Keyword(s):  
Tensile Strength ◽  
High Temperatures ◽  
Vickers Hardness ◽  
Temperature Range ◽  
Universal Device ◽  
Time Strength ◽  
Increasing Temperature

AbstractIn this paper are presented investigation results of tensile strength and elongation of selected alloys from Pt-Rh system. Samples with the content of rhodium in a concentration range of 7-40% (wt.) were studied. Studies were performed in the temperature range 1100-1500°C at a stress of 2-20 MPa. A universal device for measuring hardness was used to measure the Vickers hardness. For investigation of time strength and elongation at high temperatures, the device Mayes MK2 TC/10 was used. It was found that the value of tensile strength increases with increasing rhodium content, and decreases with increasing temperature. Elongation decreases to 7% Rh, then increases with increasing rhodium content to 15% and then slowly decreases again. With increasing temperature there is a slight increase in elongation.

A Transmission Electron Microscopical Investigation of Phase Transformations in TiNi

1980 ◽  
Vol 38 ◽  
pp. 340-341
Author(s):  
P. Moine ◽  
G. M. Michal ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Applied Stress ◽  
Structural Changes ◽  
Microscopical Investigation ◽  
Temperature Range ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Diffraction Effects ◽  
Microscopy Images

Premartensitic effects in near equiatomic TiNi have been pointed out by several authors(1-5). These include anomalous contrast in electron microscopy images (mottling, striations, etc. ),diffraction effects(diffuse streaks, extra reflections, etc.), a resistivity peak above Ms (temperature at which a perceptible amount of martensite is formed without applied stress). However the structural changes occuring in this temperature range are not well understood. The purpose of this study is to clarify these phenomena.

EXPLORING THE INTERNAL STRENGTHS AND WEAKNESSES OF THE ORGANIZATION

2018 ◽  
Vol 28 (1) ◽  
pp. 73-78
Author(s):  
Venelin Terziev ◽  
Marin Georgiev
Keyword(s):  
20Th Century ◽  
Structural Changes ◽  
Cumulative Effect ◽  
Professional Culture ◽  
Social Revolution ◽  
Modern Times ◽  
The World ◽  
History Of ◽  
Scientific Technical ◽  
The Subject

The subject of this article is the genesis of the professional culture of personnel management. The last decades of the 20th century were marked by various revolutions - scientific, technical, democratic, informational, sexual, etc. Their cumulative effect has been mostly reflected in the professional revolution that shapes the professional society around the world. This social revolution has global consequences. In addition to its extensive parameters, it also has intensive ones related to the deeply-rooted structural changes in the ways of working and thinking, as well as in the forms of its social organization. The professional revolutions in the history of Modern Times stem from this theory.Employees’ awareness and accountability shall be strengthened. The leader must be able to formulate and bring closer to the employees the vision of the organization and its future goal, to which all shall aspire. He should pay attention not to the "letter" but to the "spirit" of this approach.

Tensile properties of finger-jointed lumber under high-temperature and oxygen-free conditions

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kong Yue ◽  
Feng Wang ◽  
Weidong Lu ◽  
Zhongqiu Tang ◽  
Zhangjing Chen ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
High Temperatures ◽  
Variable Temperature ◽  
Physical Property ◽  
Solid Wood ◽  
Nitrogen Atmosphere ◽  
Thermal Physical Property ◽  
Electron Microscopy Analysis ◽  
Increasing Temperature

Abstract A model for engineered wood was developed that considers the parallel-to-grain tensile strength of finger-jointed lumber at high temperatures relevant to fire conditions. The finger-jointed lumber was composed of Douglas fir, larch, and poplar wood with phenol-resorcinol-formaldehyde (PRF) as an adhesive. The tensile properties of the finger-jointed lumber were evaluated at high temperatures under oxygen-free conditions, i.e. in a nitrogen atmosphere. A combination of chemical and thermal-physical property analysis of the PRF adhesive and microscopic observations on the glueline was used to discuss the reduction of tensile strength of the parallel-to-grain finger-jointed lumber at variable temperature. The results show that the tensile strength of the finger-jointed lumber decreased linearly with increasing temperature. The parallel-to-grain tensile strength of the PRF finger-jointed samples at 20 and 280 °C were 84 and 5% of the tensile strength of the solid wood at 20 °C, respectively. The thermal-physical properties and scanning electron microscopy analysis revealed that the pyrolysis intensity of the PRF adhesive was lower than that of the wood at 220 °C or higher.

scholarly journals Dynamic Single-Fiber Pull-Out of Polypropylene Fibers Produced with Different Mechanical and Surface Properties for Concrete Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 722
Author(s):  
Enrico Wölfel ◽  
Harald Brünig ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Christina Scheffler
Keyword(s):  
Tensile Strength ◽  
Dynamic Loading ◽  
Melt Spinning ◽  
Structural Changes ◽  
High Surface ◽  
Single Fiber ◽  
Scanning Calorimetry ◽  
Matrix Interaction ◽  
Pull Out ◽  
Fiber Matrix

In strain-hardening cement-based composites (SHCC), polypropylene (PP) fibers are often used to provide ductility through micro crack-bridging, in particular when subjected to high loading rates. For the purposeful material design of SHCC, fundamental research is required to understand the failure mechanisms depending on the mechanical properties of the fibers and the fiber–matrix interaction. Hence, PP fibers with diameters between 10 and 30 µm, differing tensile strength levels and Young’s moduli, but also circular and trilobal cross-sections were produced using melt-spinning equipment. The structural changes induced by the drawing parameters during the spinning process and surface modification by sizing were assessed in single-fiber tensile experiments and differential scanning calorimetry (DSC) of the fiber material. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements were applied to determine the topographical and wetting properties of the fiber surface. The fiber–matrix interaction under quasi-static and dynamic loading was studied in single-fiber pull-out experiments (SFPO). The main findings of microscale characterization showed that increased fiber tensile strength in combination with enhanced mechanical interlocking caused by high surface roughness led to improved energy absorption under dynamic loading. Further enhancement could be observed in the change from a circular to a trilobal fiber cross-section.

scholarly journals XIX.—Magnetization and Resistance of Nickel Wire at High Temperatures. Part II.

1907 ◽  
Vol 45 (3) ◽  
pp. 547-554
Author(s):  
C. G. Knott
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Electrical Resistance ◽  
British Association ◽  
Nickel Wire ◽  
Present Communication ◽  
Association Meeting ◽  
The Subject ◽  
The Wire

The experiments which form the subject of the present communication were carried out two years ago, and supplement results already published. A brief note of some of the results was read before the Society in June 1904, and was also read before the British Association Meeting at Cambridge in August of the same year.The previous paper discussed the effect of high temperature on the relation between electrical resistance and magnetization when the wire was magnetized longitudinally, that is, in the direction in which the resistance was measured.The present results have to do with the effect of high temperature on the relation between resistance and magnetization when the magnetization was transverse to the direction along which the resistance was measured.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

ON MEASUREMENT OF THERMAL CONDUCTIVITY AT HIGH TEMPERATURES

1961 ◽  
Vol 39 (7) ◽  
pp. 1029-1039 ◽  
Author(s):  
M. J. Laubitz
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
High Temperatures ◽  
Mathematical Analysis ◽  
Temperature Range ◽  
Linear Heat ◽  
Flow Systems

A method is given for exact mathematical analysis of linear heat flow systems used in measuring thermal conductivity at high temperatures. It is shown that a popular version of such a system is very sensitive to the alignment of its components, which seriously limits the temperature range of its satisfactory use.

Mechanical And Superconducting Properties Of Cu-Nb3Sn In Situ Produced Composite Wires

1981 ◽  
Vol 12 ◽  
Author(s):  
A. Kolb-Telieps ◽  
B.L. Mordike ◽  
M. Mrowiec
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Wide Temperature Range ◽  
Volume Fraction ◽  
Superconducting Properties ◽  
Temperature Range ◽  
Composite Wires ◽  
Strength And Ductility

ABSTRACTCu-Nb composite wires were produced from powder, electrolytically coated with tin and annealed to convert the Nb fibres to Nb 3Sn. The content was varied between 10 wt % and 40 wt %. The superconducting properties of the wires were determined. The mechanical properties, tensile strength, yield strength and ductility were measured as a function of volume fraction and deformation over a wide temperature range. The results are compared with those for wires produced by different techniques.

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