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Institution

ExxonMobil

CompanyIrving, Texas, United States
About: ExxonMobil is a company organization based out in Irving, Texas, United States. It is known for research contribution in the topics: Catalysis & Polymerization. The organization has 16969 authors who have published 23758 publications receiving 535713 citations. The organization is also known as: Exxon Mobil Corporation & Exxon Mobil Corp..
Topics: Catalysis, Polymerization, Polymer, Hydrocarbon, Alkyl


Papers
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Journal ArticleDOI
TL;DR: In this article, the entanglement molecular weight for a polymer melt, Me, is related by a power law to p, the packing length of the polymer species, and the observed and predicted values of Mr for two species, 1,4-polybutadiene and polyisobutylene, have been found to agree, within the uncertainties, with the projected values.
Abstract: We have shown in previous studies that the entanglement molecular weight for a polymer melt, Me, is related by a power law to p, the packing length of the polymer species. We now find that power laws also describe the molecular weights characterizing the melt viscosity, Mc marking the onset of entanglement effects and Mr the crossover to the reptation form. The packing length exponents for Me, Mc, and Mr differ significantly, however. The long-held notion that the ratio Mc/Me has the same value for all species is therefore incorrect. Further, the observed and predicted values of Mr for two species, 1,4-polybutadiene and polyisobutylene, have been found to agree, within the uncertainties, with the projected values. Finally, the variations with packing length are such that all three characteristic molecular weights would appear to converge on the same value near p = 9 A. As yet, no species with such a large packing length has been completely studied rheologically. But the range is not outlandish and is clea...

415 citations

Journal ArticleDOI
TL;DR: Early development of marine electromagnetic methods, dating back about 80 years, was driven largely by defense/military applications, and use for these purposes continues to this day as mentioned in this paper, although the hydrocarbon exploration industry was aware of this work, the shallow-water environments being explored at that time were not ideally suited for its use.
Abstract: Early development of marine electromagnetic methods, dating back about 80 years, was driven largely by defense/military applications, and use for these purposes continues to this day. Deepwater, frequency-domain, electric dipole-dipole, controlled-source electromagnetic (CSEM) methods arose from academic studies of the oceanic lithosphere in the 1980s, and although the hydrocarbon exploration industry was aware of this work, the shallow-water environments being explored at that time were not ideally suited for its use. Low oil prices and increasingly successful results from 3D seismic methods further discouraged investment in costly alternative geophysical data streams. These circumstances changed in the late 1990s, when both Statoil and ExxonMobil began modeling studies and fieldtrials of CSEM surveying in deep water (around 1000 m or deeper), specifically for characterizing the resistivity of previously identified drilling targets. Trials offshore Angola in 2000–2002 by both these companies showed that ...

412 citations

Journal ArticleDOI
T. E. Fischer1, H. Tomizawa1
02 Sep 1985-Wear
TL;DR: Friction and wear of Si3N4 sliding on itself were measured at room temperature in different gaseous and liquid environments as discussed by the authors, showing that wear occurs by two fracture mechanisms: within 1 μm of the surface, asperity contact produces very large local stresses and cracking on a very fine scale; 3-5 μm deeper the fracture follows weaknesses of the material and is intergranular fracture with some transgranular cleavage.

403 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a theory of stress relaxation in star polymer melts with no adjustable parameters beyond those measurable in linear melts, and incorporate the effect of higher Rouse modes on star arm retraction and the Colby−Rubinstein scaling of entanglement length within dynamic dilution.
Abstract: We present a theory of stress relaxation in star polymer melts with no adjustable parameters beyond those measurable in linear melts. We incorporate the effect of higher Rouse modes on star arm retraction and the Colby−Rubinstein scaling of entanglement length within “dynamic dilution”. Our results for G‘‘(ω) compare well with experimental data, with excellent agreement in shape and within a factor of 2 in time and modulus scales.

396 citations

Journal ArticleDOI
03 Apr 2015-Science
TL;DR: Atomic force microscopy monitoring in ZDDP-containing lubricant base stock at elevated temperatures monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts, highlighting the critical role of stress and thermal activation.
Abstract: Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation.

393 citations


Authors

Showing all 16987 results

NameH-indexPapersCitations
David A. Weitz1781038114182
Avelino Corma134104989095
Peter Hall132164085019
James A. Dumesic11861558935
Robert H. Crabtree11367848634
Costas M. Soukoulis10864450208
Nicholas J. Turro104113153827
Edwin L. Thomas10460640819
Israel E. Wachs10342732029
Andrew I. Cooper9938934700
Michael J. Zaworotko9751944441
Enrique Iglesia9641631934
Yves J. Chabal9451933820
George E. Gehrels9245430560
Ping Sheng9059337141
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20234
202236
2021302
2020340
2019366
2018438