摘要:
An ethylene polymerization process is disclosed. Ethylene is polymerized in two slurry reaction zones with a C6-C10 alpha-olefin in the presence of a single-site catalyst capable of making a high molecular weight polyolefin. The process yields medium density and linear low density polyethylene having a bimodal molecular weight distribution and a melt index from about 0.10 to about 0.80. Films from the polyethylene have superior impact properties.
摘要:
Disclosed is a polyethylene composition. The composition comprises single-site multimodal resin A and single-site multimodal resin B, wherein resin A differs from resin B in molecular weight, in monomeric composition, in density, in long chain branch concentration or distribution, or in combinations thereof. Disclosed is also a method for making the polyethylene composition. The method comprises polymerizing, in the presence of two or more single-site catalysts, ethylene or its mixture with a C3-C10 α-olefin to form a first multimodal resin and continuing the polymerization in the presence of the same catalysts but in a different hydrogen concentration, in a different monomer composition, or at a different temperature to form a second multimodal resin.
摘要:
Resins comprising a relatively high-density, low-molecular-weight polyethylene component and a relatively low-density, high-molecular-weight ethylene copolymer component and methods of making the resins are disclosed. The rheological polydispersity of the high-density component exceeds that of either the resin or the low-density component. The resins are valuable for making films, sheets, coatings, pipes, fibers, and molded articles having a favorable balance of good stiffness and excellent environmental stress crack resistance.
摘要:
A method for making multilayer thin films is disclosed. The method of comprises orienting a thick multilayer film in the machine direction at a drawdown ratio effective to produce a multilayer thin film. The thick multilayer film has a thickness within the range of 1 mil to 5 mils and comprises at least one layer of a linear low density polyethylene (LLDPE) and at least one layer of a high density polyethylene (HDPE) or a medium density polyethylene (MDPE).
摘要:
A multilayer thin film is disclosed. The multilayer thin film has a thickness within the range of about 0.1 mil to about 1 mil and comprises at least one layer of a linear low density polyethylene (LLDPE) and at least one layer of a high density polyethylene (HDPE) or a medium density polyethylene (MDPE). The multilayer thin film has high tear strength and an excellent combination of other properties.
摘要:
Improved multi-phase polypropylene composites are provided. The compositions are comprised of a polypropylene base resin, a non-compatible dispersed phase which can be a polymer or filler material and a propylene-ethylene copolymer grafted with a carboxylic acid or carboxylic acid derivative.
摘要:
A high-temperature solution process for polymerizing ethylene is disclosed. The polymerization is performed in the presence of a preassembled bimetallic Ziegler-Natta catalyst and an aluminum compound. Molecular modeling calculations predict that the bimetallic Ziegler-Natta catalyst will have good activity and improved stability versus traditional Ziegler-Natta catalysts. This makes the catalyst especially suitable for solution polymerization processes, which require a thermally robust catalyst.
摘要:
Methods for making polyolefins are disclosed. One method comprises polymerizing an olefin in the presence of a catalyst system comprising a single-site complex, an agglomerated metal oxide/clay support-activator, and an ionic borate. Including an ionic borate with the support-activator provides an unexpected boost in catalyst activity and gives polyolefins with high molecular weight and improved comonomer incorporation. In another method of the invention, an olefin is polymerized in the presence of an indenoindolyl metal alkylated complex and an agglomerated metal oxide/clay support-activator. Use of alkylated indenoindolyl complexes with the support-activators provides improved activity compared with metal halides.
摘要:
A new method for determining a pumping schedule that will produce an acceptable return on investment for a particular well includes selecting a pumping schedule, which includes an initial pumping schedule and a remaining pumping schedule, adapted for fracturing a formation around one or more perforations in the particular well. Using the initial pumping schedule, interrogate a pump data model to produce a set of fracture characteristics. A set of tiltmeter sensors and micro-seismic sensors placed adjacent the fracture in the formation will also generate a set of fracture characteristics. If the set of fracture characteristics originating from the pump data model do not substantially match the set of fracture characteristics originating from the tiltmeter sensors and the micro-seismic sensors, the pump data model must be calibrated. When the pump data model is calibrated, use the remaining pumping schedule to interrogate the calibrated pump data model thereby producing a production rate and a return on investment corresponding to the production rate. If the return on investment is not an “optimum” return on investment, change either the proportions of frac fluid and proppant in the remaining pumping schedule or the viscosity of the fluid or the injection rate until a new remaining pumping schedule is determined. When the new remaining pumping schedule interrogates the calibrated pump data model, hopefully an “optimum” production rate and an “optimum” return on investment will be determined for the particular well. The owner of the particular well or other field engineers or other decision-making personnel will then consider the “optimum” return on investment before using the remaining pumping schedule to continue fracturing the formation around the perforations in the wellbore.
摘要:
A new class of zwitterionic metallocycles is disclosed. A positively charged Group 4-10 transition metal is chelated to two heteroatoms and one of the heteroatoms has a substituent bearing a negative charge. We have found that substitution in this position stabilizes the zwitterion form of the metallocycle. The zwitterionic metallocycle is useful for olefin polymerizations.