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159results about How to "Property is limited" patented technology

High-melting polyolefin copolymer elastomers, catalysts and methods of synthesis

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.
Owner:THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV

High-melting polyolefin copolymer elastomers, catalysts and methods of synthesis

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.
Owner:BP AMOCO CORP +1

External cavity tunable compact mid-IR laser

A compact mid-IR laser device utilizes an external cavity to tune the laser. The external cavity may employ a Littrow or Littman cavity arrangement. In the Littrow cavity arrangement, a filter, such as a grating, is rotated to provide wavelength gain medium selectivity. In the Littman cavity arrangement, a reflector is rotated to provide tuning. A quantum cascade laser gain medium provides mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens for both the output lens and the external cavity lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser gain medium is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another. The small diameter aspheric output and external cavity lens each may have a diameter of 10 mm or less and each lens is positioned to provided a collimated beam output from the quantum cascade laser gain medium. The housing is hermetically sealed to provide a rugged, light weight portable MIR laser source.
Owner:DAYLIGHT SOLUTIONS

Polycrystalline superabrasive composite tools and methods of forming the same

A polycrystalline superabrasive composite tool can be produced using high pressure high temperature processes allowing for increased thermal resistance, wear resistance and toughness of abrasive tools, and additionally allowing for increased effective thickness of abrasive tools. A polycrystalline superabrasive compact can include a support substrate and a superabrasive polycrystalline layer having a diffusion bridge embedded therein that includes a carbide former. Additionally, a working layer can be attached adjacent to the superabrasive polycrystalline layer and opposite the support substrate to form a drill bit sandwich segment. The diffusion bridge matrix of the present invention allows for a new welding phase at each interface between the superabrasive polycrystalline layer and support substrate and between the polycrystalline layer and the metal working layer, thus eliminating delamination failure at the interfaces. The superabrasive polycrystalline layer can include superabrasive particles of varying particle sizes such that the final composite tool is tailored for specific abrading characteristics. The polycrystalline superabrasive composite tools can be incorporated for use in machining, drilling, grinding, cutting, polishing and similar abrasive applications.
Owner:ADICO ASIA POLYDIAMOND

Polycrystalline superabrasive composite tools and methods of forming the same

A polycrystalline superabrasive composite tool can be produced using high pressure high temperature processes allowing for increased thermal resistance, wear resistance and toughness of abrasive tools, and additionally allowing for increased effective thickness of abrasive tools. A polycrystalline superabrasive compact can include a support substrate and a superabrasive polycrystalline layer having a diffusion bridge embedded therein that includes a carbide former. Additionally, a working layer can be attached adjacent to the superabrasive polycrystalline layer and opposite the support substrate to form a drill bit sandwich segment. The diffusion bridge matrix of the present invention allows for a new welding phase at each interface between the superabrasive polycrystalline layer and support substrate and between the polycrystalline layer and the metal working layer, thus eliminating delamination failure at the interfaces. The superabrasive polycrystalline layer can include superabrasive particles of varying particle sizes such that the final composite tool is tailored for specific abrading characteristics. The polycrystalline superabrasive composite tools can be incorporated for use in machining, drilling, grinding, cutting, polishing and similar abrasive applications.
Owner:ADICO ASIA POLYDIAMOND
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