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..

Surfactant Phase Behavior and Retention in Porous Media

Abstract: Surfactant retention in reservoir rock is a major factor limiting effectiveness of oil recovery using microemulsion flooding processes. Effects of salinity and surfactant concentration on microemulsion phase behavior have a significant impact on relative magnitudes of retention attributable to adsorption vs. entrapment of immiscible microemulsion phases. Surfactant retention levels are determined by effluent sample analyses from microemulsion flow tests in Berea cores. Data for single surfactant systems containing NaCl only and multi-component surfactant systems containing monovalent and divalent cations are included. Retention is shown to increase linearly with salinity at low salt concentrations and depart from linearity with higher retentions above some critical salinity. This departure from linearity is further shown to correlate with formation of upper-phase microemulsions. Therefore, the linear trend is attributed to surfactant adsorption, and retention levels in excess of this trend are attributed to phase trapping. (28 refs.)

Method of and apparatus for enabling output power of solar panel to be maximised

Abstract: The d.c. power supplied by a photovoltaic solar panel to a load is controlled by monitoring the slope of the panel voltage vs. current characteristic and adjusting the current supplied by the panel to the load so that the slope is approximately unity. The slope is monitored by incrementally changing the panel load and indicating whether the resulting change in current derived from the panel is above or below a reference value, indicative of the panel voltage. In response to the change in the monitored current being above the reference value, the slope of a voltage vs. current curve is greater than unity and the load is adjusted to decrease the current supplied by the panel to the load. Conversely, in response to the current being less than the reference value, the slope of the voltage vs. current curve is less than unity and the load is adjusted to increase the current supplied by the panel to the load.

Probing the Early Stages of Melt Crystallization in Polypropylene by Simultaneous Small- and Wide-Angle X-ray Scattering and Laser Light Scattering

Abstract: The early stages of polymer melt crystallization using fractionated isotactic polypropylene (iPP) as a model system were investigated via simultaneous synchrotron small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) and laser light scattering (LS) techniques. Since the crystallinity in the early stages is very low, the issue of the crystallinity detection limit of WAXD was addressed. This was done by using solutions of n-paraffin (C33H68) in dodecane (C12H26) at different concentrations (as low as 1%). The precipitated fraction simulated the degree of crystallinity in polyethylene since n-paraffin essentially completely crystallized and dodecane remained liquid at the measurement temperature. A modeling method was also used to simulate the WAXD profiles to check the effect of crystal size at low crystallinity. With these two methods, we conclude that our WAXD procedure is capable of detecting crystallinity from 0.5% to 1%. During the early stages of iPP isothermal crystallization, notic...