摘要:
Monomer/solvent separation and recycle processes for continuous supercritical, solution and advanced solution polymerization processes for propylene-containing polymers and their blends are provided. The advantageous monomer/solvent separation and recycle process includes heating a polymer-lean recycle stream coming from a gravimetric separator positioned downstream of the reactor to form a heated polymer-lean recycle stream, and subsequently combining the heated polymer-lean recycle stream with the one or more homogenous reactor effluent streams to form a heated reactor effluent mixed stream. The heated reactor effluent mixed stream may then be passed through a pressure let-down valve followed and a gravimetric separator, such as to provide for reduced fouling propensity of the polymer-rich phase and sufficient heating of the polymer-rich phase to be able to pass through the remainder of the processing steps to form a propylene based polymer product without additional heat.
摘要:
Elastomeric polymer blends and processes for their production are described. Specifically, the polymer blends comprise a first polymer and a second polymer, where the first polymer comprises from about 70 wt % to about 90 wt % units derived from propylene and from about 10 wt % to about 30 wt % units derived from ethylene and/or a C4-C10 alpha-olefin, and the second polymer comprises from about 88 wt % to about 98 wt % units derived from propylene and from about 2 wt % to about 12 wt % units derived from ethylene and/or a C4-C10 alpha-olefin. The elastomeric polymer blends are further characterized by having two or more of the following properties: an overall propylene content of between about 75 wt % and about 90 wt %, a melting point between about 110° C. and about 145° C., a Vicat softening point greater than about 45° C., a tensile stress at 300% strain of less than about 500 psi (3447 kPa), as determined by a stress strain test according to ASTM D412, or an average maximum force for pellet separation of less than about 10 N in an accelerated storage stability test. The polymer blends are produced in a dual reactor process, in which the first polymer and the second polymer are prepared using differing catalyst systems.
摘要:
Provided are methods of producing polymers with broadened molecular weight and/or composition distribution in a continuous homogeneous polymerization system utilizing reactor temperature gradients, reactor polymer concentration gradients, monomer concentration gradients, catalyst concentration gradients, and combinations thereof in the polymerization reactor. Such methods are particularly suitable when utilizing metallocene catalysts and other single-site catalysts, which generally produce polymers with narrow molecular weight and composition distribution.
摘要:
Monomer/solvent separation and recycle processes for continuous supercritical, solution and advanced solution polymerization processes for propylene-containing polymers and their blends are provided. The advantageous monomer/solvent separation and recycle process includes heating a polymer-lean recycle stream coming from a gravimetric separator positioned downstream of the reactor to form a heated polymer-lean recycle stream, and subsequently combining the heated polymer-lean recycle stream with the one or more homogenous reactor effluent streams to form a heated reactor effluent mixed stream. The heated reactor effluent mixed stream may then be passed through a pressure let-down valve followed and a gravimetric separator, such as to provide for reduced fouling propensity of the polymer-rich phase and sufficient heating of the polymer-rich phase to be able to pass through the remainder of the processing steps to form a propylene based polymer product without additional heat.
摘要:
In a process for producing a propylene-based olefin homopolymer or copolymer, a monomer composition comprising propylene is contacted with a polymerization catalyst system under homogeneous polymerization conditions (such as solution, supersolution or supercritical conditions), wherein the polymerization catalyst system includes an activator and a bridged bis-indenyl transition metal (group 4) compound substituted with a carbazole (unsubstituted or substituted) at the 4 position.
摘要:
A process for fluid phase in-line blending of polymers. The process includes providing two or more reactor trains configured in parallel and a separator for product blending and product-feed separation; contacting in at least one of the parallel reactor trains olefin monomers having three or more carbon atoms, catalyst systems, optional comonomers, optional scavengers, and optional inert diluents or inert solvents, at a temperature above the solid-fluid phase transition temperature of the polymerization system and a pressure no lower than 10 MPa below the cloud point pressure of the polymerization system and less than 1500 MPa; forming a reactor effluent including a homogeneous fluid phase polymer-monomer mixture in each parallel reactor train; combining the reactor effluent from each parallel reactor; passing the combined reactor effluent through the separator; maintaining the temperature and pressure within the separator above the solid-fluid phase transition point but below the cloud point pressure and temperature to form a fluid-fluid two-phase system including a polymer-rich blend phase and a monomer-rich phase; and separating the monomer-rich phase from the polymer-rich blend phase. The separated monomer-rich phase is recycled to the polymerization reactor bank. The polymer-rich blend phase is conveyed to a downstream finishing stage for further monomer stripping, drying and/or pelletizing to form a polymer product blend.
摘要:
The present invention provides a highly elongated member of substantially uniform cross-sectional configuration which is capable of improved service as a stiffening support in an optical fiber cable. Such elongated member is the product of melt extrusion through an appropriate orifice of a thermotropic liquid crystalline polymer (as described). The resulting elongated member has been found to offer significant advantages when compared to stiffening supports heretofore proposed for use in optical fiber cables.
摘要:
Procedure for the specific isolation of total DNA content of bacterial germs of different samples, in the course of which the cells are lysated, the DNA content of the lysate is bound selectively, it is washed and then the desalinated linear polymer nucleic acid is eluted from the binding surface in an aqueous solution. Before cell lysis the nonviable bacterial cells are separated from the viable cells on the basis of their different cell surface physical-chemical characteristics, the viable cells of the sample are kept and then lysated using a mechanical and/or enzymatic, favourably lysozyme enzymatic method. After this exclusively double-stranded DNA deriving from the lysate of viable cells is bound on a —SiO2—TiO2- matrix containing chemically activated —OH and dodecylamine groups, and after washing it, the desalinated linear polymer nucleic acid is eluted in an aqueous solution.
摘要:
A process for hydrotreating a first aromatics- and sulfur-containing hydrocarbon feed using a fresh supported CoMo catalyst, includes treating the fresh catalyst under first hydrotreating conditions with a second hydrocarbon feed having a lower aromatics content than the first feed.
摘要:
Isotactic polypropylene ethylene-propylene copolymer blends and in-line processes for producing. The blends may have between 1 and 50 wt % of isotactic polypropylene with a melt flow rate of between 0.5 and 20,000 g/10 min and a melting peak temperature of 145° C. or higher, and wherein the difference between the DSC peak melting and the peak crystallization temperatures is less than or equal to 0.5333 times the melting peak temperature minus 41.333° C., and between 50 and 99 wt % of ethylene-propylene copolymer including between 10 wt % and 20 wt % randomly distributed ethylene with a melt flow rate of between 0.5 and 20,000 g/10 min, wherein the copolymer is polymerized by a bulk homogeneous polymerization process, and wherein the total regio defects in the continuous propylene segments of the copolymer is between 40 and 150% greater than a copolymer of equivalent melt flow rate and wt % ethylene polymerized by a solution polymerization process.