Abstract: The invention relates to a process for the preparation of a multimodal polyolefin polymer in a first polymerization reactor and a second polymerization reactor connected in series, wherein a first polyolefin polymer is prepared in the first polymerization reactor in suspension in the presence of hydrogen and a second polyolefin polymer is prepared in the second polymerization reactor in the presence of a lower concentration of hydrogen than in the first polymerization reactor, the process comprising: a) withdrawing a suspension of solid polyolefin particles in a suspension medium from the first polymerization reactor, wherein the suspension medium comprises hydrogen and a hydrocarbon mixture having an initial boiling point of at least 50° C. and a final boiling point of at most 120° C.; b) feeding the suspension to a flash drum having a pressure controlled by a vacuum pump, wherein the pressure of the flash drum is less than 0.

Abstract: The invention relates to a process for the preparation of a multimodal polyolefin polymer in a first polymerization reactor and a second polymerization reactor connected in series, wherein a first polyolefin polymer is prepared in the first polymerization reactor in suspension in the presence of hydrogen and a second polyolefin polymer is prepared in the second polymerization reactor in the presence of a lower concentration of hydrogen than in the first polymerization reactor, the process comprising: a) withdrawing a suspension of solid polyolefin particles in a suspension medium from the first polymerization reactor, wherein the suspension medium comprises hydrogen and a hydrocarbon mixture having an initial boiling point of at least 50° C. and a final boiling point of at most 120° C.; b) feeding the suspension to a flash drum having a pressure controlled by a vacuum pump, wherein the pressure of the flash drum is less than 0.

Abstract: A method of precipitating a poly(arylene ether) includes preparing a poly(arylene ether) solution comprising a poly(arylene ether) and a solvent, combining the poly (arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprising a poly(arylene ether) solid, separating the poly(arylene ether) solid from the poly(arylene ether) dispersion to form an isolated poly(arylene ether) solid, determining a particle size distribution of the poly(arylene ether) solid prior to separating the poly(arylene ether) solid from the poly(arylene ether) dispersion, and adjusting a precipitation parameter in response to the particle size distribution. Although the measured particle size distribution is very different from the particle size distribution of the solid poly(arylene ether) ultimately isolated, it is useful for controlling the process. The method may be automated to rapidly adjust precipitation conditions in response to the particle size distribution measurements.

Abstract: A method of precipitating a poly(arylene ether) includes preparing a poly(arylene ether) solution comprising a poly(arylene ether) and a solvent, combining the poly (arylene ether) solution with an antisolvent to form a poly(arylene ether) dispersion comprising a poly(arylene ether) solid, separating the poly(arylene ether) solid from the poly(arylene ether) dispersion to form an isolated poly(arylene ether) solid, determining a particle size distribution of the poly(arylene ether) solid prior to separating the poly(arylene ether) solid from the poly(arylene ether) dispersion, and adjusting a precipitation parameter in response to the particle size distribution. Although the measured particle size distribution is very different from the particle size distribution of the solid poly(arylene ether) ultimately isolated, it is useful for controlling the process. The method may be automated to rapidly adjust precipitation conditions in response to the particle size distribution measurements.