Abstract: Polymerization processes and reactor systems for producing multimodal ethylene polymers are disclosed in which at least one loop reactor and at least one fluidized bed reactor are utilized. Configurations include a loop reactor in series with a fluidized bed reactor and two loop reactors in series with a fluidized bed reactor.

Abstract: Polymerization processes and reactor systems for producing multimodal ethylene polymers are disclosed in which at least one loop reactor and at least one fluidized bed reactor are utilized. Configurations include a loop reactor in series with a fluidized bed reactor and two loop reactors in series with a fluidized bed reactor.

Abstract: The present application relates to a polypropylene composition having a melt flow rate MFR.2 (230° C.) measured according to ISO 1133 in the range of 5 to 50 g/10 min, to a composition comprising the polypropylene composition and one or more additive(s) in an amount of up to 4 wt.-%, based on the total weight of the composition, to a process for the preparation of the polypropylene composition and an article comprising the polypropylene composition as well as the use of the polypropylene composition for decreasing the brittle-to-ductile transition temperature.

Abstract: A process comprising polymerizing olefin monomers and optionally comonomers in a first reactor vessel, thereby forming a raw product stream comprising polymerized solids, unreacted monomer and optionally comonomer, the polymerized solids comprising olefin polymer, volatile organic compounds (VOC) and catalyst system. Then the polymerized solids are contacted with a catalyst poison selected from carbon monoxide, carbon dioxide, oxygen, water, alcohols, amines, or mixtures thereof, thereby forming a passivated stream. The passivated stream is maintained in an agitated state within a second reactor. The passivated stream within the second reactor is then contacted with a circulating gas comprising unreacted monomer for a residence time, thereby reducing the concentration of VOC in the polymerized solids by at least 10 wt % compared to the level before entering the second reactor, thereby forming a purified olefin polymer solids stream.

Abstract: The invention relates to a process for the preparation of a propylene homopolymer or a propylene ?-olefin random copolymer comprising the step of a) preparing a propylene homopolymer or a propylene ?-olefin random copolymer, wherein the ?-olefin is chosen from the group consisting of ethylene, and ?-olefins having 4 to 10 carbon atoms, for example 1-butene or 1-hexene by contacting at least the propylene and optionally ?-olefin, with a catalyst in a gas-phase reactor at a temperature T1 and a pressure P1, wherein T1 is chosen in the range from 75 to 90° C., for example in the range from 77 to 85° C., for example in the range from 78 to 83° C., wherein P1 is chosen in the range from 22 to 30 bar to prepare a propylene homopolymer (A?) or a propylene ?-olefin random copolymer (A?).

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 slurry polymerization process for the preparation of polyethylene in a reactor cascade of two or more polymerization reactors wherein monomers are polymerized in the polymerization reactors which include a reactor outlet arranged in each reactor bottom for feeding a reactor slurry to a subsequent polymerization reactor and for emptying the polymerization reactor.

Abstract: The present invention describes a process for continuous fractionation of CTO (crude tall oil) to RTD (refined tall diesel), said process comprising:—when removing a stream of TOP (tall oil pitch) the CTO is fed through at least two evaporation zones arranged in series so that one stream of CTO is fed from a first evaporation zone to a second evaporation zone, wherein a TOP stream is produced and fed from the second evaporation zone, wherein a first vapor stream is produced within the first evaporation zone and a second vapor stream is produced within the second evaporation zone and wherein there is a temperature difference of at least 10° C.

Abstract: The invention relates to a process for producing a polypropylene composition by sequential polymerization the polypropylene composition having an improved balanced combination of high flowability, high stiffness and impact, and high level of optical properties.

Abstract: A continuous method for producing a diene elastomer is provided. The method comprises a polymerization reaction of a catalytic system with at least one conjugated diene monomer to be polymerized in solution in a solvent. The catalytic system is based on at least a rare earth organic salt and an alkylating agent, in at least two full polymerization reactors in series. A portion of the conjugated diene monomer to be polymerized is introduced into a polymerization reactor subsequent to the first polymerization reactor.

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: To provide a continuous production apparatus and a continuous production method for an aromatic polymer which enable resource conservation, energy conservation, and equipment costs reduction. A continuous production method for an aromatic polymer having an ether bond or an imide bond, the method including: (a) supplying a polymerization solvent and a reaction raw material to a continuous production apparatus including a plurality of reaction vessels; (b) performing a polycondensation reaction in the polymerization solvent in at least one of the reaction vessels to form a reaction mixture; and (c) successively moving the reaction mixture to each of the reaction vessel, the steps (a), (b), and (c) being performed in parallel; wherein an ether bond or an imide bond is formed by the polycondensation reaction; respective gas phase parts of the plurality of reaction vessels communicate with one another; and a pressure of each of the gas phase parts is uniform.

Abstract: There is disclosed an antifoam component for a mechanical device which includes a poly(acrylate) copolymer. The antifoam component has improved foam performance in finished fluids utilizing dibutyl hydrogen phosphite compounds, such as driveline fluids. A lubricating composition comprising a) at least one oil of lubricating viscosity; and b) an antifoam component comprising a poly(acrylate) copolymer. The poly(acrylate) copolymer, b) may include (i) from about 30 wt % up to about 99 wt % of a (meth)acrylate monomer having C1 to C4 alkyl esters of (meth)acrylic acid; and (ii) from about 1 wt % up to about 70 wt % of a fluorinated (meth)acrylate monomer.

Abstract: A continuous flow reactor, a method of performing a continuous flow reaction, and a method of controlling a moveable wall of a reaction chamber of a continuous flow reactor. The reactor comprising: an inlet; an outlet; and a reaction chamber, between the inlet and the outlet and providing a flow path therebetween, the reaction chamber having a moveable wall; the reactor further comprising: a pressure sensor configured to monitor a fluid pressure in the continuous flow reactor; and a controller, operable to adjust the position of the moveable wall, and thereby change a volume of the reaction chamber, based on the monitored fluid pressure.

Abstract: A method of preparing a conjugated diene-based polymer is provided including: a step of polymerizing a first conjugated diene-based monomer in solution in a first polymerization reactor to prepare a first polymer solution including a first conjugated diene-based polymer; a step of polymerizing a second conjugated diene-based monomer in solution in a second polymerization reactor to prepare a second polymer solution including a second conjugated diene-based polymer; a step of supplying a first fluid separated from the first polymer solution to a first purification unit and purifying the first fluid; and a step of supplying a second fluid separated from the second polymer solution to a second purification unit and purifying the second fluid. An apparatus for preparing a conjugated diene-based polymer is also provided.

Abstract: The present invention relates to a continuous olefin polymerization process comprising polymerization of at least one olefin monomer in at least two serial vapor phase polymerization reactors containing an agitated bed of forming polymer particles, comprising a polymer particles transfer step wherein forming polymer particles are transferred from an upstream reactor to a downstream reactor comprising in a repeating sequence the steps of discharging at least one charge of polymer powder and reactive gases from the upstream reactor into a gas-solid separator; collecting the polymer powder separated in the gas-solid separator in a pressure transfer chamber; increasing the pressure in the pressure transfer chamber with a pressurizing gas to a pressure that is higher than the operating pressure of the downstream reactor; and discharging the polymer powder from the pressure transfer chamber into the downstream reactor, wherein said process reduces the carry-over of reactive gases from the upstream reactor to the do

Abstract: Techniques regarding catalyzing one or more ring-opening polymerizations within one or more flow reactors using one or more organometallic bases are provided. For example, one or more embodiments described herein can comprise a method, which can include forming a polymer, via a ring-opening polymerization within a flow reactor, from a cyclic monomer in the presence of an organometallic base and a primary alcohol initiator.

Abstract: The present invention provides a method for producing a polyethylene resin in which gel or fish eye formation is greatly reduced, by controlling various reaction conditions such as the supply flow rate ratio of the monomers to each reactor, the temperature range of each reactor, and the temperature range of the mixing region, in the method for producing a polyethylene resin which is applied to produce a polyethylene resin for a protective film of display.

Abstract: This invention relates to a non-phthalate catalyst system for olefin polymerization. The non-phthalate catalyst system comprises (a) a solid Ziegler-Natta catalyst composition comprising a transition metal, a Group 2 metal, and one or more halogens; and one or more internal electron donor compounds; and (b) one or more external electron donor compounds.

Abstract: A process comprising polymerizing olefin monomers and optionally comonomers in a first reactor vessel, thereby forming a raw product stream comprising polymerized solids, unreacted monomer and optionally comonomer, the polymerized solids comprising olefin polymer, volatile organic compounds (VOC) and catalyst system. Then the polymerized solids are contacted with a catalyst poison selected from carbon monoxide, carbon dioxide, oxygen, water, alcohols, amines, or mixtures thereof, thereby forming a passivated stream. The passivated stream is maintained in an agitated state within a second reactor. The passivated stream within the second reactor is then contacted with a circulating gas comprising unreacted monomer for a residence time, thereby reducing the concentration of VOC in the polymerized solids by at least 10 wt % compared to the level before entering the second reactor, thereby forming a purified olefin polymer solids stream.

Abstract: A gas-phase polymerization reactor for the gas-phase polymerization of olefins including a polymerization zone having a recycle line for (a) withdrawing reaction gas from the reactor, (b) leading the reaction gas through a heat-exchanger for cooling, and (c) feeding the reaction gas back to the reactor, wherein the recycle line has the heat-exchanger, a centrifugal compressor having variable guide vanes, and a butterfly valve, and a related process for preparing an olefin polymer in the gas-phase polymerization reactor.

Abstract: Embodiments of the invention described herein relate to a polyethylene polymer composition suitable for use in the manufacture of packaging articles, flexible films and/or sheets. In one embodiment, the copolymer comprises a polyethylene resin with density 0.918 g/cm3 to about 0.935 g/cm3, G? at G?(500 Pa) value, as determined from Dynamic Mechanical Analysis at 190° C., of less than 40 Pa, Mz/Mw of greater than 2, CDBI50 of greater than 60. Other embodiments relate to polymer compositions with defined molecular characteristics and formulations suitable for use in the manufacture of articles including films, sheets, bags and pouches with improved creep resistance and high toughness and a good balance of film stiffness and processability in monolayer and/or multi-layer film structures.

Abstract: A process including contacting one or more monomers, at least one catalyst system, and a condensing agent including a majority of propane under polymerizable conditions to produce a polyolefin polymer is provided.

Abstract: The present invention relates to a reactor system for a multimodal polyethylene composition comprising: (a) first reactor; (b) hydrogen removal unit arranged between the first reactor and a second reactor comprising at least one vessel connected with a depressurization equipment, preferably selected from vacuum pump, compressor, blower, ejector or a combination thereof, the depressurization equipment allowing to adjust an operating pressure to a pressure in a range of 100-200 kPa (abs); (c) the second reactor; and (d) a third reactor and use thereof as a pipe.

Abstract: An eductor, a process and apparatus for gas phase polymerization of olefins in a polymerization reactor are disclosed. The process and apparatus employ an eductor which has an inlet which makes a bend of less than about 90° toward the outlet after entering the mixing chamber of the eductor.

Abstract: Process for preparing an olefin polymer including the step of polymerizing an olefin in the presence of a polymerization catalyst and hydrogen as molecular weight regulator in a gas-phase polymerization reactor to yield growing polymer particles, the reactor including three or more polymerization zones and at least two thereof are sub-zones of a polymerization unit wherein the growing polymer particles flow downward in a densified form and at least one polymerization zone has a ratio of hydrogen to the sum of olefins which is a factor of at least 1.5 lower than the ratio of hydrogen to the sum of olefins in the polymerization zone having the highest ratio of hydrogen to the sum of olefins and a factor of at least 1.5 higher than the ratio of hydrogen to the sum of olefins in the polymerization zone having the lowest ratio of hydrogen to the sum of olefins.

Abstract: A method and apparatus produce silicon-carbon composite materials through a chemical vapor deposition or a thermal disposition process in a fluidized bed reactor on a semi-continuous basis. The produced silicon-carbon composite has a unique structure that silicon particles are uniformly dispersed, bonded and embedded into the carbon conductive matrix and forming a secondary structure. The produced silicon-carbon composite can be used as advanced anode materials for lithium battery and other electrochemical energy storage device.

Abstract: Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Abstract: Apparatuses and processes that produce multimodal polyolefins, and in particular, polyethylene resins, are disclosed herein. This is accomplished by using two reactors in series, where one of the reactors is a multi-zone circulating reactor that can circulate polyolefin particles through two polymerization zones optionally having two different flow regimes so that the final multimodal polyolefin has improved product properties and improved product homogeneity.

Abstract: The present invention is directed to a polypropylene composition, said polypropylene composition comprising two different polypropylene fractions (PP1) and (PP2), wherein the first polypropylene (PP1) has a weight molecular weight Mw in the range of above 45 kg/mol to below 65 kg/mol and a melting temperature of at least 140° C.

Abstract: The invention relates to a process and system for the continuous polymerization of one or more ?-olefin monomers comprising the steps of: a) introducing catalyst and/or polymer from at least one loop reactor to at least one second reactor b) withdrawing fluids from the at least one second reactor c) cooling fluids comprising the withdrawn fluids with a cooling unit d) introducing the cooled fluids to a separator to separate at least part of the liquid from these fluids to form a liquid phase and a gas/liquid phase e) introducing the gas/liquid phase below to the reactor below a distribution plate f) introducing the liquid phase to a settling tank to separate liquid from fines that settle down in the settling tank g) introducing liquid from the settling tank upstream of the cooling unit, h) introducing the slurry comprising solid polymer particles from the settling tank to the at least one loop reactor.

Abstract: The present invention relates to an olefin polymerization process for producing propylene copolymer composition (P), wherein propylene, C4 to C10 ?-olefin and optionally ethylene are reacted in the presence of a Ziegler-Natta catalyst in a multistage polymerization process comprising at least two polymerization reactors, wherein the copolymer composition is bimodal with respect to the content of C4 to C10 ?-olefin and, if present, to ethylene. Further, the invention is directed to the propylene copolymer composition being bimodal with respect to the content of C4 to C10 ?-olefin and optionally to ethylene, and use of said propylene copolymer compositions for producing articles.

Abstract: This invention relates to a process for forming polymer including: polymerizing a monomer dissolved in a solvent in the presence of a catalyst system under conditions to obtain a first effluent stream including a solution of the polymer and the solvent; heating the first effluent stream in at least one spiral heat exchanger to produce a second effluent stream, where the first effluent stream flows through the spiral heat exchanger in a cross-flow direction relative to spirals of the spiral heat exchanger and performing a separation on the second effluent stream to produce: a third effluent stream including polymer substantially free of the solvent; and a recycle stream including the solvent and unreacted monomer. Processes for devolatilizing a polymer stream are also provided herein.

Abstract: The present invention relates to a process for the continuous preparation of a polyolefin in a reactor from one or more ?-olefin monomers of which at least one is ethylene or propylene, wherein the reactor comprises a fluidized bed, an expanded section located at or near the top of the reactor, a distribution plate located at the lower part of the reactor and an inlet for a recycle stream located under the distribution plate, wherein the process comprises—feeding a polymerization catalyst to the fluidized bed in the area above the distribution plate—feeding the one or more ?-olefin monomers to the reactor—withdrawing the polyolefin from the reactor—circulating fluids from the top of the reactor to the bottom of the reactor, wherein the circulating fluids are cooled using a heat exchanger, resulting in a cooled recycle stream comprising liquid, and wherein the cooled recycle stream is introduced into the reactor using the inlet for the recycle stream wherein a stream comprising a thermal run away reducing agen

Abstract: Disclosed is a method for producing a polyolefin including: (1) a step (1) of polymerizing one or more olefins in solution polymerization or slurry polymerization in the presence of a polymerization catalyst to produce a polymer solution, (2) a step (2) of taking out the polymer solution obtained in the step (1), and adding a catalyst deactivator in the polymer solution to deactivate the polymerization catalyst, and (3) a step (3) of removing volatile components in vacuum from the polymer solution where the polymerization catalyst has been deactivated, and including, between the step (2) and the step (3), a step of adding an additive to the polymer solution when the water concentration in the polymer solution is 5 ppm by mass or less.

Abstract: A process to form an ethylene-based polymer comprises polymerizing a reaction mixture comprising ethylene, at least one monomeric chain transfer agent, and at least one chain transfer agent system comprising at least one chain transfer agent (CTA) in the presence of at least one free-radical initiator and in a reactor configuration comprising at least two reaction zones, reaction zone 1 and reaction zone i (i?2), wherein the reaction zone i is downstream from reaction zone 1. The ratio of “the activity of the CTA system of the feed to the first reaction zone” to the “activity of the CTA system of the cumulative feed to the reaction zone i,” (Z1/Zi), is less than or equal to (0.8?0.2*log(Cs)), wherein Cs is from 0.0001 to 10.

Abstract: A method comprising preparing a multi-component catalyst system comprising a catalyst and a cocatalyst, and adjusting the level of at least one component of the catalyst system to maintain a user-desired level of catalyst activity throughout a process, wherein the component comprises a catalyst activator and wherein the catalyst activator comprises the catalyst or the cocatalyst. A method comprising contacting a polymerization catalyst system comprising a Ziegler-Natta catalyst and a cocatalyst with a catalyst activator at least twice during a polymerization process, wherein the polymerization process is carried out in a reactor system comprising multiple reactor types.

Abstract: A polymer sheet includes a core layer containing a propylene impact copolymer (ICP), and a first additional layer comprising a first polymer composition. The propylene impact copolymer (ICP) in the core layer includes a matrix and a dispersed phase. The matrix comprises a polypropylene homopolymer or a propylene/alpha-olefin random copolymer which includes greater than 50 wt. % of units derived from propylene monomer. The dispersed phase includes a copolymer of ethylene and a C3-C8 ?-olefin. The ICP has a first melting point being greater than 100° C. (e.g., in the range of from 100° C. to 130° C.) and a second melting point. The polymer sheet can also include a second additional layer containing a second polymer composition.

Abstract: Provided is a method for producing polyphenylene ether (PPE) having excellent mechanical properties, heat aging resistance, and color, and in which the content of impurities such as low molecular weight components and catalyst metal is low. The method for producing PPE includes: performing oxidative polymerization of a phenolic compound in a polymerization solution containing the phenolic compound, a catalyst, and an aromatic solvent to obtain a PPE mixed liquid; precipitating PPE to obtain a slurry containing particulate PPE through addition of a polar solvent to the PPE mixed liquid; solid-liquid separating the slurry to obtain wet PPE particles; washing the wet PPE particles to obtain PPE particles through at least one cycle of a washing and solid-liquid separation process in which washing is performed with a washing liquid containing an aromatic solvent and a polar solvent, and in which solid-liquid separation is performed; and drying the PPE particles.

Abstract: A multilayer film is prepared from a high impact strength polyethylene (HI polyethylene); a Ziegler Natta catalyzed polyethylene (Z/N polyethylene) and a high pressure low density polyethylene (LD polyethylene) with i) at least one skin layer consists essentially of HI polyethylene and ii) at least one core layer comprises a blend of Z/N polyethylene and said LD polyethylene. The HI polyethylene has a density of from 0.915 to about 0.930 g/cc and a normalized impact strength of at least about 300 g/mil. The amount of HI polyethylene is from about 30 to about 55 weight % (based on the combined weights of the HI+Z/N+LD polyethylenes). The films described herein are readily prepared on blown film equipment and provide an excellent balance of mechanical properties.

Abstract: The invention relates to a reactor in the form of a VK tube (VK: simplified continuous), for the polymerisation of polyamides, the reactor being subdivided into an upper and lower reactor region, which are controllable independently of each other. Likewise, the invention relates to a method for the production of polyamides in which such a reactor is used.

Abstract: The present disclosure provides a process for producing propylene-based polymer. The process includes contacting, under polymerization conditions in a gas phase polymerization reactor, propylene monomer and optionally one or more comonomers with a Ziegler-Natta catalyst composition. The process includes maintaining the temperature of a reaction zone of the reactor at a temperature from greater than 72° C. to less than or equal to 85° C., and forming a propylene-based polymer having a molecular weight (Mw) greater than 100,000, and a Mz+1/Mz less than 2.20. The resultant propylene-based polymer is advantageous in fiber applications.

Abstract: The present disclosure generally relates to a slurry polymerization process for the preparation of polyethylene in the presence of a Ziegler catalyst and aluminum alkyl co-catalyst in at least one polymerization reactor, in which process suspension medium comprising a concentration of aluminum alkyl co-catalyst is recycled to the polymerization, the concentration of aluminum alkyl co-catalyst in the recycled suspension medium is determined; and the amount of fresh aluminum alkyl co-catalyst fed to the polymerization is adjusted to maintain a targeted aluminum alkyl co-catalyst concentration in the recycled suspension medium.

Abstract: A system and method for startup of a polyolefin reactor temperature control system having a first reactor temperature control path, a second reactor temperature control path, and a shared temperature control path. In some embodiments, during startup the second reactor temperature control path is configured to allow the temperature of a second reactor to rise due to the heat of the exothermic polymerization reaction occurring within reactor until reaching a predetermined setpoint temperature. In other embodiments, during startup a first reactor temperature control path is configured to include a heat exchanger used as a cooler, and a second reactor temperature control path is configured to include a heat exchanger used as a heater, to raise the temperature of the second reactor until reaching a predetermined setpoint temperature.

Abstract: The present invention relates to a method for preparing an ABS graft copolymer. According to the present invention, provided is a method for preparing an ABS graft copolymer capable of improving surface gloss by inducing the formation of bimodal particles through the formation of existing ABS resin particles and ABS resin particles having a relatively small diameter.

Abstract: The present invention relates to a process for producing water-absorbing polymer particles, wherein an aqueous monomer solution is polymerized and the monomer solution is prepared using steam condensate.

Abstract: The present technology relates to a polyethylene composition suitable for producing small articles such as flexible and collapsible tubes by blow molding comprising: 1) a density from 0.948 to 0.955 g/cm3; 2) a MIF/MIP ratio from 12 to 25; 3) a MIF from 25 to 40 g/10 min; 4) a Mz from 1000000 to 2000000 g/mol; and 5) a long-chain branching index, LCBI, equal to or greater than 0.55.

Abstract: Process for the polymerization of olefins in a polymerization reactor system including (i) a gas phase reactor having a gas outlet and one or more withdrawal lines for withdrawal of a polymer-containing stream, (ii) a recycle loop for recycling gas exiting the reactor through the gas outlet back to the reactor, (iii) a polymer separation system for separating reactants from the polymer product in the withdrawn polymer-containing stream, and (iv) a recycle system for recycling reactants removed from the reactor in the withdrawn polymer-containing stream back to the reactor. A scavenger is introduced directly into one or more of the recycle loop, the polymer separation system and the recycle system.

Abstract: Process for polymerizing olefins in a polymerization reactor system including at least first and second introduction points by which the same reaction component may be introduced directly at different locations on the reactor system. At a first time, the reaction component is introduced through at least the first introduction point, such that a proportion X of the reaction component which is introduced through the first and second introduction points is introduced through the first introduction point. At a second, later, time the same reaction component is introduced through at least the second introduction point and such that a proportion Y of the reaction component which is introduced through the first and second introduction points is introduced through the first introduction point. Y is less than X, and at least one of the first and second introduction points is located on the reactor system at a location not on the reactor.

Abstract: Polymerization process, in particular for the polymerization of monomer selected from ethylene and propylene in a reaction system containing at least three reactors operated in series. The process includes (a) polymerizing monomer in a first reactor having a volume of at least 50 m3 to produce a first polymer, (b) passing the first polymer to a second reactor and polymerizing monomer in the second reactor to produce a second polymer containing the first polymer and polymer produced in the second reactor, and (c) passing the second polymer to a third reactor and polymerizing monomer in the third reactor to produce a third polymer containing the second polymer and polymer produced in the third reactor. The polymerizations are performed such that between 0.01 and 5 w % of the total mass of the third polymer is polymer produced in the second reactor.