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..

Graphite Intercalation Compounds

Abstract: Publisher Summary Twenty years ago, Walter Rudorff wrote a review for the series entitled “Graphite Intercalation Compounds” (R1). It was one of the four definitive articles to come out in 1959 and 1960 (HI, C1, U1), a period of intense activity in graphite research. One have now again reached the “fever pitch,” with not only the appearance of several new articles (E l , H2, W1), but also the convening of the first international conference dedicated exclusively to graphite compounds (H3 ). In the following, one shall concentrate on the work performed between 1974 and the present. The interlayer voids are frequently attacked to yield a periodic sequence of filled and empty spaces. The stage of a compound is defined as the ratio of host layers to guest layers, so that a first-stage compound, in which every interlayer void is filled, is the most concentrated. Historically, compounds of graphite have been placed in three categories, depending on the strength of interaction between the reacting species and graphite.

Propylene polymers for films

Abstract: This invention relates generally to crystalline propylene polymers, to methods for their production and to methods for their use in film applications. Specifically, this invention relates to crystalline propylene polymers comprising both propylene homopolymer and propylene copolymer. The compositions are prepared using metallocene catalyst systems comprising at least two metallocenes in a polymerization process that involves the sequential or parallel polymerization of propylene homopolymer and copolymer using propylene with a small amount of comonomer, preferably ethylene. The polymerization is catalyzed by a dual metallocene catalyst system. The resulting polymers have a broad, bimodal molecular weight distribution. The resulting polymers are excellent for use in the production of biaxially oriented films or non-oriented films. Films prepared with these propylene polymers have a significantly broader processability range and can be evenly stretched at lower temperature compared to films prepared from traditional propylene polymer.

Impact of Longer-Term Modest Climate Shifts on Architecture of High-Frequency Sequences (Cyclothems), Pennsylvanian of Midcontinent U.S.A.

Abstract: Pennsylvanian glacioeustatic cyclothems exposed in Kansas and adjacent areas provide a unique opportunity to test models of the impact of relative sea level and climate on stratal architecture. A succession of eight of these high-frequency sequences, traced along dip for 500 km, reveal that modest climate shifts from relatively dry-seasonal to relatively wet-seasonal with a duration of several sequences (~600,000 to 1 million years) had a dominant impact on facies, sediment dispersal patterns, and sequence architecture. The climate shifts documented herein are intermediate, both in magnitude and duration, between previously documented longer-term climate shifts throughout much of the Pennsylvanian and shorter-term shifts described within individual sequences. Climate indicators are best preserved at sequence boundaries and in incised-valley fills of the lowstand systems tracts (LST). Relatively drier climate indicators include high-chroma paleosols, typically with pedogenic carbonates, and plant assemblages that are dominated by gymnosperms, mostly xerophytic walchian conifers. The associated valleys are small ( 4 km wide and >20 m deep), and dominated by quartz sandstones derived from distant source areas, reflecting large drainage networks. Transgressive systems tracts (TST) in all eight sequences generally are characterized by thin, extensive limestones and thin marine shales, suggesting that the dominant control on TST facies distribution was the sequestration of siliciclastic sediment in updip positions. Highstand systems tracts (HST) were significantly impacted by the intermediate-scale climate cycle in that HSTs from relatively drier climates consist of thin marine shales overlain by extensive, thick regressive limestones, whereas HSTs from relatively wetter climates are dominated by thick marine shales. Previously documented relative sea-level changes do not track the climate cycles, indicating that climate played a role distinct from that of relative sea-level change. These intermediate-scale modest climate shifts had a dominant impact on sequence architecture. This independent measure of climate and relative sea level may allow the testing of models of climate and sediment supply based on modern systems.