988 results about "Mole fraction" patented technology

This invention relates to high melting polyolefin copolymers suitable as thermoplastic elastomers and catalysts and methods for their synthesis. These elastomeric olefin copolymers are characterized by a mole fraction of crystallizable component Xc from about 30 to about 99%; low glass transition temperatures, below -20° C., and typically below -50° C.; melting points above about 90° C.; high molecular weights; a molecular weight distribution MW / Mn< / =10; and a narrow composition distribution between chains of < / =15%. The novel copolymers of the invention range from reactor blends to multiblock copolymers that can be sequentially fractionated into fractions of differing crystallinities, which fractions nevertheless show compositions of comonomers which differ by less than 15% from the parent polymer (reactor product). The invention also relates to a process for producing such copolymers by utilizing an unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalyst that is capable of interconverting between states with different copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where ri>rf the polymer can be characterized as multiblock; where ri<rf, the result is a polymer blend and where ri / rf is close to 1, the resulting polymer is a mixture of blend and multiblock. The metallocene catalysts of the invention are able to interconvert between more than two states, with embodiments of four states being shown in FIG. 2.

A GaN / AlN superlattice is formed over a GaN / sapphire template structure, serving in part as a strain relief layer for growth of subsequent layers (e.g., deep UV light emitting diodes). The GaN / AlN superlattice mitigates the strain between a GaN / sapphire template and a multiple quantum well heterostructure active region, allowing the use of high Al mole fraction in the active region, and therefore emission in the deep UV wavelengths.

A solid polymethylaluminoxane composition is provided having uniform particle diameter in the form of fine particles of less than 5 μm employed to polymerize olefins with high polymerization activity without silica. A method for manufacturing thereof, a polymerization catalyst, and a method for manufacturing a polyolefin are also provided. The solid polymethylaluminoxane composition: has an aluminum content within a range of 36 mass % to 43 mass %; has a mole fraction of methyl groups derived from trimethylaluminum moieties relative to the total number of mols of methyl groups of 12 mol % or less; and is particulate having a median diameter based on volume within a range of 0.1 μm to less than 5 μm. In a step of heating an aromatic hydrocarbon solution containing trimethylaluminum and the polymethylaluminoxane to cause solid polymethylaluminoxane composition to precipitate, prior to or during the heat treating step, a dry, inert gas is bubbled through.

Disclosed is a solid support-polymethylaluminoxane complex exhibiting a higher polymerization activity than a conventional substance and being homogeneous. Also disclosed is a method for producing an olefin-based polymer having a favorable quality using the complex and a transition metal compound. The complex comprises a coating layer containing polymethylaluminoxane and trimethylaluminum on the surface of a solid support. The coating layer comprises a solid polymethylaluminoxane composition in which (i) the content of aluminum is in a range of 36 to 41 mass % and (ii) the molar fraction of methyl groups derived from a trimethylaluminum moiety to the total number of moles of methyl groups is 12 mol % or less. Also disclosed is an olefin polymerization catalyst comprising the complex and a transition metal compound represented by general formula (III): MR5R6R7R8 as catalyst components, and a method for producing a polyolefin comprising polymerizing an olefin using the catalyst.