scholarly journals Rubber Wear and the Role of Transfer Films on Rubber Friction on Hard Rough Substrates

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
A. Tiwari ◽  
N. Miyashita ◽  
B. N. J. Persson
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Present Theory ◽  
Concrete Surface ◽  
Relative Importance ◽  
Rubber Compound ◽  
Transfer Films ◽  
Rubber Compounds ◽  
Rubber Friction

AbstractWe study the influence of rubber transfer films on the sliding friction between rectangular rubber blocks and a concrete surface. We present experimental results for the friction coefficient for a rubber compound sliding on a concrete surface contaminated by another rubber compound, for two different pairs (A, B) and (C, D) of rubber compounds. For the same rubber compounds, we present theory results which illustrate the relative importance of the viscoelastic and adhesive contribution to the sliding friction. We correlate the calculated rubber friction with the nature of the observed transfer films (or wear processes). Graphical Abstract

Role of Silicas and Silicates in Rubber Adhesion

1968 ◽  
Vol 41 (5) ◽  
pp. 1300-1311 ◽  
Author(s):  
J. R. Creasey ◽  
D. B. Russell ◽  
M. P. Wagner
Keyword(s):  
Hydrogen Bonding ◽  
Elevated Temperatures ◽  
Rubber Compound ◽  
Rubber Compounds

Abstract The addition of resoreinol plus hexamethylenetetramine and/or hydrated silicas to rubber compounds can result in increased adhesion to textiles, wire, and other rubber compounds. Silica prevents loss of adhesion on aging or at elevated temperatures. The increase in adhesion is due, depending on the system, to improved wetting and hydrogen-bonding between the rubber compound and the substrate to which it adheres.

scholarly journals EXPERIMENTAL STUDY OF THE INFLUENCE OF RUBBER PROPERTIES ON SLIDING FRICTION IN DRY CONTACT

2017 ◽  
Author(s):  
A. V. Morozov
Keyword(s):  
Friction Coefficient ◽  
Viscoelastic Properties ◽  
Sliding Friction ◽  
Normal Load ◽  
Bulk Temperature ◽  
Master Curves ◽  
Rubber Compounds ◽  
Different Temperatures ◽  
Dry Conditions ◽  
Friction Measurements

This study is devoted to experimental research of rubber friction in sliding contact with rough surface. Influence of pressure, bulk temperature and sliding velocity on friction coefficient in dry conditions is analysed for two rubber compounds with different viscoelastic properties. Grosch method of master curves construction is used for analysing of friction measurements. Such analysis is performed for different temperatures and velocities at constant normal load. The obtained friction master curves are combined into a single friction map. The friction maps demonstrate the influence of viscoelastic properties of rubber on friction coefficient in dry rough contact. Also friction maps show the influence of adhesion and hysteresis contributions into friction coefficient for different rubber compounds.

scholarly journals Rubber Adhesion and Friction: Role of Surface Energy and Contamination Films

2021 ◽  
Vol 6 ◽  
Author(s):  
A. Tiwari ◽  
T. Tolpekina ◽  
Hans van Benthem ◽  
M. K. Gunnewiek ◽  
B. N. J. Persson
Keyword(s):  
Surface Energy ◽  
Sliding Friction ◽  
Substrate Surface ◽  
Simple Relation ◽  
Work Of Adhesion ◽  
Stick Slip ◽  
Real Contact ◽  
Frictional Shear Stress ◽  
Rubber Friction

We study the influence of the surface energy and contamination films on rubber adhesion and sliding friction. We find that there is a transfer of molecules from the rubber to the substrate which reduces the work of adhesion and makes the rubber friction insensitive to the substrate surface energy. We show that there is no simple relation between adhesion and friction: adhesion is due to (vertical) detachment processes at the edge of the contact regions (opening crack propagation), while friction in many cases is determined mainly by (tangential) stick-slip instabilities of nanosized regions, within the whole sliding contact. Thus while the pull-off force in fluids may be strongly reduced (due to a reduction of the work of adhesion), the sliding friction may be only slightly affected as the area of real contact may be dry, and the frictional shear stress in the contact area nearly unaffected by the fluid.

The Role of Electric Current on Friction and Wear Behaviors of the Carbon Strip/Copper Contact Wire

2011 ◽  
Vol 80-81 ◽  
pp. 178-181
Author(s):  
Tao Ding ◽  
G.X. Chen ◽  
Z.G. Xiong ◽  
Li Xie ◽  
C.X. Wu
Keyword(s):  
Friction Coefficient ◽  
Electric Current ◽  
Friction And Wear ◽  
Sliding Friction ◽  
Material Transfer ◽  
Friction Process ◽  
Contact Wire ◽  
Pin On Disc ◽  
Worn Surface

A serial of experiment studies on the friction and wear behaviors of the carbon strip/copper contact wire under the electric current were carried on the pin-on-disc tester. The results indicated that the tribology performances were remarkably affected by the electric current. The friction coefficient decreases with an increase of electric current. However, the were volume increases with increasing of electric current, and the worn surface of carbon strip become severer and severer with the increasing electric current. Therefore, the electric current play roles of lubrication and accelerating wear in the process of electrical sliding friction. By the analysis of EDX, it is seen that the oxide wear exists in electrical sliding friction process. Observing the worn surfaces of copper pan sample, it is found that the electric current increases the material transfer of carbon strip.

A Quantitative Theory for the Computation of Tire Friction Under Severe Conditions of Sliding

1986 ◽  
Vol 14 (1) ◽  
pp. 44-72 ◽  
Author(s):  
C. M. Mc C. Ettles
Keyword(s):  
Friction Coefficient ◽  
Flash Temperature ◽  
Contact Conditions ◽  
Quantitative Form ◽  
Heating Effects ◽  
Rubber Friction ◽  
Viscoelastic Effects ◽  
Tire Friction ◽  
Pavement Friction ◽  
Metal Polymer

Abstract It is proposed that tire-pavement friction is controlled by thermal rather than by hysteresis and viscoelastic effects. A numerical model of heating effects in sliding is described in which the friction coefficient emerges as a dependent variable. The overall results of the model can be expressed in a closed form using Blok's flash temperature theory. This allows the factors controlling rubber friction to be recognized directly. The model can be applied in quantitative form to metal-polymer-ice contacts. Several examples of correlation are given. The difficulties of characterizing the contact conditions in tire-pavement friction reduce the model to qualitative form. Each of the governing parameters is examined in detail. The attainment of higher friction by small, discrete particles of aluminum filler is discussed.

Population Control (Review Article)

1961 ◽  
Vol 1 (3) ◽  
pp. 89-98
Author(s):  
Karol J. Krotki
Keyword(s):  
Population Control ◽  
Review Article ◽  
Small Enterprise ◽  
Opportunity Costs ◽  
Relative Importance ◽  
Factual Information ◽  
Undue Influence ◽  
Clear Cut ◽  
Economic Considerations

Discussions about the role of small enterprise in economic development tend to remain inconclusive partly because of the difficulty of assessing the relative importance of economic and non-economic objectives and partly because of the dearth of factual information on which to base an economic calculus. It is probably true, moreover, that, because of a lack of general agreement as to the economic case for or against small enterprise, non-economic considerations, including some merely romantic attitudes toward smallness and bigness, tend to exert an undue influence on public policies. There may, of course, be no clear-cut economic case. And noneconomic considerations should and will inevitably weigh significantly in policy decisions. If, however, some of the economic questions could be settled by more and better knowledge, these decisions could more accurately reflect the opportunity costs of pursuing non-economic objectives.

scholarly journals Role of propagule pressure in colonization success: disentangling the relative importance of demographic, genetic and habitat effects

2013 ◽  
Vol 26 (8) ◽  
pp. 1691-1699 ◽  
Author(s):  
R. A. Hufbauer ◽  
A. Rutschmann ◽  
B. Serrate ◽  
H. Vermeil de Conchard ◽  
B. Facon
Keyword(s):  
Propagule Pressure ◽  
Relative Importance ◽  
Colonization Success

scholarly journals The Arctic as a “Strategic” and “Important” Chinese Foreign Policy Interest: Exploring the Role of Labels and Hierarchies in China’s Arctic Discourses

2021 ◽  
pp. 186810262110186
Author(s):  
Patrik Andersson
Keyword(s):  
Foreign Policy ◽  
International Relations ◽  
Political Discourse ◽  
Chinese Foreign Policy ◽  
The Arctic ◽  
Relative Importance ◽  
Precise Understanding ◽  
New Frontier ◽  
Political Priority

Research confirms that China is becoming more engaged in the Arctic. However, international relations scholarship often extrapolates from relatively few instances of activity to wide-ranging claims about Chinese priorities. Fortunately, Chinese political discourse is organised by labels that allow us to study how the Arctic is classified and ranked along China’s other foreign policy priorities. This article analyses two such classifications – “important maritime interest” and “strategic new frontier,” exploring how they have come about, what they mean, and how they add political priority to the Arctic. It argues that hierarchies are constructed in two ways: by adding gradients and by including/excluding categories of priority. It views categories as performative: they not only convey information about character and relative importance of interests but are also used for achieving different objectives. By focusing on foreign policy classifications, the article contributes to a more nuanced and precise understanding of China’s Arctic interests.

Study of the role of Chlamydia, Mycoplasma, Ureaplasma and other microaerophilic and aerobic bacteria in uterine infections of mares with reproductive disorders

2003 ◽  
Vol 51 (1) ◽  
pp. 45-52 ◽  
Author(s):  
László Szeredi ◽  
M. Tenk ◽  
I. Schiller ◽  
Keyword(s):  
Pathogenic Bacteria ◽  
Anaerobic Bacteria ◽  
Aerobic Bacteria ◽  
Relative Importance ◽  
Reproductive Disorders ◽  
Taylorella Equigenitalis

In six healthy mares and 24 mares showing reproductive disorders swab samples were taken from the fossa clitoridis to isolate Taylorella equigenitalis, and from the uterus to isolate mycoplasmas, ureaplasmas and other aerobic bacteria. Swab samples were also taken from the uterus for Chlamydiaantigen ELISA and ChlamydiaPCR studies. The uterus of 27 mares was examined cytologically, and biopsy samples were taken from the endometrium for histological examinations and for immunohistochemical examinations aimed at the detection of chlamydiae. T. equigenitalis, mycoplasmas, ureaplasmas and chlamydiae could not be detected from any of the mares examined. Aerobic facultative pathogenic bacteria were isolated from mares with endometritis in four cases. In 18 out of 22 mares with endometritis (82%) no infective agents could be demonstrated. Further studies are needed to elucidate the relative importance of non-infectious causes of endometritis and of anaerobic bacteria often detectable in the uterus in the aetiology of the reproductive disorders observed.

The role of the rate of application of the tangential force in determining the static friction coefficient

Wear ◽  
1973 ◽  
Vol 24 (3) ◽  
pp. 381-385 ◽  
Author(s):  
V.I. Johannes ◽  
M.A. Green ◽  
C.A. Brockley
Keyword(s):  
Friction Coefficient ◽  
Tangential Force ◽  
Static Friction ◽  
Static Friction Coefficient
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