ExxonMobil

About: ExxonMobil is a company organization based out in Irving, Texas, United States. It is known for research contribution in the topics: Catalysis & Polymer. 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..

Time-Dependent Reactive Coupling at Polymer-Polymer Interfaces

Abstract: X ABSTRACT: Using recently calculated rate coefficients for reactive coupling of chains at polymer-polymer interfaces, we describe the diffusion-controlled growth of diblock copolymer at the interface between dissimilar molten homopolymer films. The growth exhibits several regimes, successively controlled by (1) the quasilocal reaction rate near the interface, (2) center-of-mass diffusion of reactive homopolymer to the interface, and (3) the diffusion barrier presented by the growing copolymer layer. Our results can be tested by time-dependent measurements of the copolymer coverage or concentration of reacted coupling groups.

Correlation of steel corrosion in pipe flow with jet impingement and rotating cylinder tests

Abstract: The relationship of laboratory fluid flow corrosion test techniques to flow-accelerated corrosion in field applications and the parameters required to apply laboratory data effectively in the field were studied. Single-phase, aqueous, sweet corrosion of steel in turbulent pipe flow (12.7 mm and 25.4 mm diam) was correlated to corrosion in jet impingement and rotating cylinder tests. All tests were conducted simultaneously, using the same test fluid to minimize environmental variables and to allow a direct, realistic comparison of test methods. Rotating cylinder electrode corrosion rates did not correlate with pipe flow based on wall shear stress or mass transfer for flow-accelerated corrosion of carbon (C) steel in the environment studied. Jet impingement corrosion rates for the test ring at r/r0=3 correlated with pipe flow based on wall shear stress. The general equation for flow-accelerated corrosion of C steel under turbulent flow conditions in this environment was expressed as: Rcorr = a τwb ...

Rheology of Three-Arm Asymmetric Star Polymer Melts

Abstract: We present experimental and theoretical results for the linear rheology of melts of entangled, three-arm asymmetric polyisoprene stars. Asymmetric three-arm stars, in which two arms have the same length and the third is shorter, cross over from starlike to linear-like stress relaxation as the length of the third arm varies. We combine recent theories of stress relaxation in symmetric stars and in linear melts to predict the dynamic modulus of the asymmetric stars. For stars with short arm molecular weights of a few entanglement lengths, our theory underestimates the effective drag caused by the short arm, even when polydispersity effects are included. This unexplained discrepancy does not appear in a recent comparison of a related theory with measurements on polyisoprene H-polymers.

Tomographically Enhanced Full Wavefield Inversion

Abstract: Method for improving convergence in gradient-based iterative inversion of seismic data ( 101 ), especially advantageous for full wavefield inversion The method comprises decomposing the gradient into two (or more) components ( 103 ), typically the migration component and the tomographic component, then weighting the components to compensate for unequal frequency content in the data ( 104 ), then recombining the weighted components ( 105 ), and using the recombined gradient to update ( 106 ) the physical properties model ( 102 )