Abstract: A method for monitoring polymerization processes can include reacting by polymerization a feedstock in the presence of a catalyst in a reactor to produce an effluent comprising a polymer and a solvent; measuring a density of the effluent; and calculating a monomer conversion rate and/or a polymerization rate for the polymerization based on the density of the effluent. A system for monitoring polymerization processes can include a reactor containing an effluent comprising a solvent, a polymer, and a monomer; a flash vessel fluidly coupled to the reactor to receive the effluent from the reactor; and an inline density meter fluidly coupled to the reactor, placed between the reactor and the flash vessel, and configured to measure a density of the effluent.

Abstract: This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as amorphous silica, as quenching agents, typically in solution or bulk polymerization processes.

Abstract: A method for producing block copolymers can include polymerizing a feedstock comprising a monomer and a comonomer under first polymerization conditions in the presence of a catalyst in a reactor to produce a first effluent comprising a first polyolefin block, an unreacted monomer, and an unreacted comonomer; blending the first effluent with a coordinative chain transfer polymerization agent to produce a mixture; and polymerizing the mixture in a separator under second polymerization conditions to cause the unreacted monomer and the unreacted comonomer to polymerize onto one end of the first polyolefin block as a second polyolefin block, thereby forming a block copolymer, wherein the first polyolefin block has a first comonomer content and the second polyolefin block has a second comonomer content that is different than the first comonomer content. The method can further include polymerizing in presence of a second coordinative chain transfer polymerization agent in a second separator.

Abstract: A method for producing a polyolefin with a wide molecular weight distribution can comprise: polymerizing one or more monomers in the presence of a catalyst system in a loop reactor to produce a polyolefin product having a polydispersity index of 2.5 to 8, wherein the loop reactor comprises two or more reactors in series, and wherein the loop reactor has a loop thermal gradient of 50° C. to 150° C. and/or a standard deviation of inter-component thermal gradients along the loop reactor of 10° C. to 50° C.

Abstract: A process for the synthesis of a granular polymer, the process comprising (a) providing an active polymerization mixture that includes polymer, monomer, catalyst and optional solvent; (b) introducing a hydroxy-containing diaryl acetyl compound to the active polymerization mixture to thereby provide an inactive polymer mixture; (c) separating the polymer solution into a first stream and a second stream, where the first stream includes the polymer and the hydroxy-containing diaryl acetyl compound, and the second stream includes the monomer and the optional solvent; and (d) fabricating granules from the first stream.

Abstract: The present disclosure discloses a polarization-maintaining hollow-core antiresonant fiber. An inner layer of the polarization-maintaining hollow-core antiresonant fiber includes first thin walls, second thin walls, and third thin walls. The present disclosure introduces high birefringence through the wall thickness difference between the first thin wall and the second thin wall, and effectively amplifies a birefringence effect achieved by the wall thickness difference through quasi multi-symmetric structures of the first thin walls and the second thin walls. In addition, the present disclosure reduces the transmission loss and suppresses the leakage of light through the inner layer, particularly, the third thin walls of the inner layer, so that the fiber of the present disclosure realizes polarization maintaining, and meanwhile, reduce the loss as far as possible.

Abstract: A method for producing gradient copolymers can include polymerizing a reaction mixture comprising a monomer and a comonomer in the presence of a metallocene catalyst in a loop reactor, wherein in the loop reactor a gradient monomer weight percent in the reaction mixture is about 3 wt % to about 50 wt %, thereby forming a gradient copolymer.

Abstract: A method broadening a molecular weight distribution and/or broadening a chemical composition distribution of the polyolefin product can include: polymerizing a feedstock in the presence of a metallocene catalyst in a loop reactor to produce a polyolefin product, the feedstock comprising two or more monomers; and adjusting a polymerization parameter selected from the group consisting of decreasing a recycle ratio, increasing a polymer concentration, increasing a LRSU number, and any combination thereof.

Abstract: A method for determining polymer concentration can include synthesizing a polymer in a reactor under a set of parameters, wherein the reactor comprises a solution mixture having a refractive index, and wherein the solution mixture comprises a solvent, a polymer, and optionally a monomer, wherein the solution mixture has a polymer concentration; measuring the refractive index of the solution mixture; comparing the refractive index of the solution mixture with a calibration curve; and identifying the polymer concentration in the solution mixture. A system for determining polymer concentration can include a reactor containing a solution mixture comprising a solvent, a polymer, and optionally a monomer; a flash vessel fluidly coupled to the reactor to receive the solution mixture from the reactor; and a first refractometer fluidly coupled to the reactor, placed between the reactor and the flash vessel, and configured to measure a refractive index of the solution mixture.

Abstract: Disclosed is an ultralow loss hollow-core antiresonant fiber, which includes an outer layer structure, a hollow-core area and a plurality of closed cavities. The radial section of the inner surface of the outer layer structure is a circle with a first radius. In the circumferential direction of the inner surface of the outer layer structure, the plurality of the closed cavities are spaced from one another and are distributed uniformly and circumferentially. Each closed cavity includes: an outermost wall serving as a first thin wall, and the radial section of the outermost wall is a fan shape or a circle with a second radius. Each closed cavity further includes: second thin walls located in the inner space surrounded by the inner surface of the outermost wall, and the end surfaces of the second thin walls are annular thin-walled structures with thin-walled spacers arranged in the centers.

Abstract: The present disclosure discloses a polarization-maintaining hollow-core antiresonant fiber. An inner layer of the polarization-maintaining hollow-core antiresonant fiber includes first thin walls, second thin walls, and third thin walls. The present disclosure introduces high birefringence through the wall thickness difference between the first thin wall and the second thin wall, and effectively amplifies a birefringence effect achieved by the wall thickness difference through quasi multi-symmetric structures of the first thin walls and the second thin walls. In addition, the present disclosure reduces the transmission loss and suppresses the leakage of light through the inner layer, particularly, the third thin walls of the inner layer, so that the fiber of the present disclosure realizes polarization maintaining, and meanwhile, reduce the loss as far as possible.

Abstract: Disclosed is an ultralow loss hollow-core antiresonant fiber, which includes an outer layer structure, a hollow-core area and a plurality of closed cavities. The radial section of the inner surface of the outer layer structure is a circle with a first radius. In the circumferential direction of the inner surface of the outer layer structure, the plurality of the closed cavities are spaced from one another and are distributed uniformly and circumferentially. Each closed cavity includes: an outermost wall serving as a first thin wall, and the radial section of the outermost wall is a fan shape or a circle with a second radius. Each closed cavity further includes: second thin walls located in the inner space surrounded by the inner surface of the outermost wall, and the end surfaces of the second thin walls are annular thin-walled structures with thin-walled spacers arranged in the centers.

Abstract: This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as lecithin, as quenching agents, typically in solution or bulk polymerization processes.

Abstract: This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as amorphous silica, as quenching agents, typically in solution or bulk polymerization processes.

Abstract: This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as amorphous silica, as quenching agents, typically in solution or bulk polymerization processes.

Abstract: The present disclosure provides methods for the production of polymer blends using multiple reactors arranged in parallel. The methods comprise: providing a first feed comprising propylene to a first reactor operated in parallel with a second reactor; catalytically converting the first feed in the first reactor under polymer formation conditions utilizing a first catalyst to form a first product mixture; separating the first product mixture into a first fraction comprising polypropylene and a second fraction comprising unreacted propylene; providing a second feed comprising one or more elastomeric monomers to the second reactor; catalytically converting the second feed in the second reactor under polymer formation conditions utilizing a second catalyst different from the first catalyst to form a second product mixture comprising an elastomeric polymer; and blending the first fraction with the second product mixture downstream from the first reactor and the second reactor to form a polymer blend.

Abstract: A method for producing gradient copolymers can include polymerizing a reaction mixture comprising a monomer and a comonomer in the presence of a metallocene catalyst in a loop reactor, wherein in the loop reactor a gradient monomer weight percent in the reaction mixture is about 3 wt % to about 50 wt %, thereby forming a gradient copolymer.

Abstract: A method for producing block copolymers can include polymerizing a feedstock comprising a monomer and a comonomer under first polymerization conditions in the presence of a catalyst in a reactor to produce a first effluent comprising a first polyolefin block, an unreacted monomer, and an unreacted comonomer; blending the first effluent with a coordinative chain transfer polymerization agent to produce a mixture; and polymerizing the mixture in a separator under second polymerization conditions to cause the unreacted monomer and the unreacted comonomer to polymerize onto one end of the first polyolefin block as a second polyolefin block, thereby forming a block copolymer, wherein the first polyolefin block has a first comonomer content and the second polyolefin block has a second comonomer content that is different than the first comonomer content. The method can further include polymerizing in presence of a second coordinative chain transfer polymerization agent in a second separator.

Abstract: A method for determining polymer concentration can include synthesizing a polymer in a reactor under a set of parameters, wherein the reactor comprises a solution mixture having a refractive index, and wherein the solution mixture comprises a solvent, a polymer, and optionally a monomer, wherein the solution mixture has a polymer concentration; measuring the refractive index of the solution mixture; comparing the refractive index of the solution mixture with a calibration curve; and identifying the polymer concentration in the solution mixture. A system for determining polymer concentration can include a reactor containing a solution mixture comprising a solvent, a polymer, and optionally a monomer; a flash vessel fluidly coupled to the reactor to receive the solution mixture from the reactor; and a first refractometer fluidly coupled to the reactor, placed between the reactor and the flash vessel, and configured to measure a refractive index of the solution mixture.

Abstract: A method for monitoring polymerization processes can include reacting by polymerization a feedstock in the presence of a catalyst in a reactor to produce an effluent comprising a polymer and a solvent; measuring a density of the effluent; and calculating a monomer conversion rate and/or a polymerization rate for the polymerization based on the density of the effluent. A system for monitoring polymerization processes can include a reactor containing an effluent comprising a solvent, a polymer, and a monomer; a flash vessel fluidly coupled to the reactor to receive the effluent from the reactor; and an inline density meter fluidly coupled to the reactor, placed between the reactor and the flash vessel, and configured to measure a density of the effluent.