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..

Supported catalyst for 1-olefin(s) (co)polymerization

Abstract: This invention relates to a supported catalyst composition useful in the polymerization of olefins and to a method for its production. The catalyst is formed by first reacting a trialkylaluminum compound with a transition metal metallocene, and subsequently reacting the resulting material with the undehydrated support material to form a solid product containing at least 20 grams of support material per milimole of transition metal. The resulting supported catalyst has a level of activity comparable to that of conventionally made supported catalysts which are achieved at active metal loadings which are reduced from the loadings used in the previously known metallocene-alumoxane catalysts by at least 20 %, and preferably 50 %. The invention particularly relates to the use of undehydrated silica gel containing from 6 to 20 per cent by weight adsorbed water as the catalyst support material.

Calcium Modification of Spinel Inclusions in Aluminum-Killed Steel: Reaction Steps

Abstract: Calcium treatment is a well-established way to modify solid alumina inclusions to liquid or partially liquid calcium aluminates. Spinels (Al2O3·xMgO) can also form in liquid steel after aluminum deoxidation. Like alumina, the spinels can be modified readily to liquid inclusions by a calcium treatment. The modification of spinels was studied by observing the transient evolution of inclusions, in laboratory and industrial heats. Spinel modification involves the preferential reduction of MgO from the spinel, with Mg dissolving in the steel, and it proceeds through transient calcium sulfide formation, just like in the case of alumina inclusions. Because magnesium dissolves in steel after the calcium treatment of spinels, the reoxidation of the melt will produce new spinels.

Base-line model for identifying the bioaccumulation potential of chemicals

Abstract: The base-line modeling concept presented in this work is based on the assumption of a maximum bioconcentration factor (BCF) with mitigating factors that reduce the BCF. The maximum bioconcentration potential was described by the multi-compartment partitioning model for passive diffusion. The significance of different mitigating factors associated either with interactions with an organism or bioavailability were investigated. The most important mitigating factor was found to be metabolism. Accordingly, a simulator for fish liver was used in the model, which has been trained to reproduce fish metabolism based on related mammalian metabolic pathways. Other significant mitigating factors, depending on the chemical structure, e.g. molecular size and ionization were also taken into account in the model. The results (r(2)=0.84) obtained for a training set of 511 chemicals demonstrate the usefulness of the BCF base line concept. The predictability of the model was evaluated on the basis of 176 chemicals not used in the model building. The correctness of predictions (abs(logBSF(Obs)-logBCF(Calc))=0.75)) for 59 chemicals included within the model applicability domain was 80%.

Percolation in an oil-continuous microemulsion.

Abstract: Static and dynamic scaling behaviors of electrical conductivity and dielectric constant are obtained near the percolation transition in an oil-continuous microemulsion. Conductivity data are in agreement with a dynamic percolation picture and inconsistent with the static percolation expected from a bicontinuous structure. The dielectric constant, on the other hand, is found to be insensitive to the dynamical process.

Low permeability nanocomposites

Abstract: The present invention includes blends of a halogenated elastomer such as a butyl rubber or an interpolymer of, on one embodiment, a C4 to C7 isomonoolefin, a para-methylstyrene and a para-(halomethylstyrene), the interpolymer having been pre-mixed with an exfoliating compound and clay, the entire blend forming a nanocomposite in one embodiment. The clay may or may not have undergone an additional exfoliating treatment prior to blending with the halogenated elastomer. The interpolymer/clay mixture forms a distinct phase in the nanocomposite blend of the invention. The blend of the invention has improved air barrier properties and is suitable as an air barrier.