Characteristic intervals in suspension polymerisation reactors: An experimental and modelling study

Jahanzad, Fatemeh; Sajjadi, Shahriar; Brooks, Brian W.

doi:10.1016/j.ces.2005.04.063

Cited by 49 publications

(82 citation statements)

References 34 publications

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“…The initial properties of the liquid-liquid dispersion will strongly impact the properties of the final polymer beads or pearls [10]. Suspension polymerization can then be divided into three different steps [11,12]: (i) a liquid-liquid dispersion step, (ii) the reaction steps in which the polymerizing droplets can agglomerate leading to the final polymer particle size and (iii) a step enabling to reach a conversion between 80% and 90% without change in the polymer particle size. Fig.…”

Section: Introductionmentioning

confidence: 99%

Liquid–liquid dispersion in a continuous oscillatory baffled reactor – Application to suspension polymerization

Lobry

Lasuye²,

Gourdon

et al. 2015

Chemical Engineering Journal

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.Liquid-liquid dispersion in a continuous oscillatory baffled reactor -Application to suspension polymerization b s t r a c tReducing energy costs, improving safety, minimizing waste are the current aims of chemical engineering. Process intensification in fine chemistry has been extensively studied but less work refers to heterogeneous reactions involving two liquid phases. This paper focuses on batch to continuous suspension polymerization transposition and especially on the liquid-liquid dispersion step. The main features of suspension polymerization reaction are based on (i) the initial liquid-liquid dispersion requiring a controlled size and narrow distribution and (ii) on the control of the final particle size during the agglomeration step by avoiding fouling which is a bottleneck for continuous flow. For the continuous transposition, liquid-liquid dispersion and reaction studies are carried out in continuous oscillatory baffled reactor (COBR) which is a multipurpose reactor. Its suitability to overcome the bottlenecks is demonstrated through the investigation of the oscillating and flow conditions or the dispersed phase holdup. A controlled droplet size distribution can be achieved. Oscillation is the main parameter responsible for droplet breakage. The suitable conditions to obtain stable dispersion are determined. For one of the first times, COBR is used for suspension polymerization.

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Section: Introductionmentioning

confidence: 99%

Liquid–liquid dispersion in a continuous oscillatory baffled reactor – Application to suspension polymerization

Lobry

Lasuye²,

Gourdon

et al. 2015

Chemical Engineering Journal

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“…From this gure it is clear that the rate of polymerisation was not affected by the PVA concentration and droplet size, which agrees with the literature. 39 It also shows that there is a dramatic increase in the rate of polymerisation around the conversion of 0.30, which is known to be due to the gel effect. The onset of the gel effect occurred at about 40 min and as a result conversion reached a value as high as 90% in few minutes.…”

Section: 839mentioning

confidence: 93%

“…A suspension polymerisation reaction typically passes through four stages which are; transition, quasi steady-state, growth or sticky and identication stages. 39 In the current work, the transition stage did not exist, as droplets had already been formed. The conversions were measured versus time for polymerisation runs using a low and high concentration of PVA, and are plotted in Fig.…”

Section: 839mentioning

confidence: 98%

“…Using PVA with a different degree of hydrolysis may adversely affect the polymer morphology. 7,8,38,39 We used a PVA with a molecular weight and degree of hydrolysis between ¼ 85 000 and 146 000 and 87-89%, respectively in this research. The effects of PVA concentration on the droplets size and CV were studied within a wide range at 0.25, 0.5, 1.0, 2.0 and 4.0 g l…”

Section: Effect Of Impeller Speedmentioning

confidence: 99%

“…39 We should note that increasing the concentration of the stabiliser will improve the stability of the droplets against coalescence only if they are not yet fully covered by the stabiliser. A full surface coverage is usually attained at the condition of CMC in the aqueous phase.…”

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confidence: 99%

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Uniform polymer beads by membrane emulsification-assisted suspension polymerisation

Alroaithi

Sajjadi

2016

RSC Adv.

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This work focuses on a two-stage polymerisation process for the production of uniform polymer beads. Highly uniform droplets were firstly produced by a stirred-vessel membrane emulsification device.Methyl methacrylate (MMA) and a specific grade of polyvinyl alcohol (PVA) were used as monomer and stabiliser, respectively. The effects of various process parameters affecting the droplet size and uniformity including feeding policy, agitation speed, stabiliser concentration, and flowrate were investigated. The evolution of droplet size and its coefficient of variation (CV) were monitored over the course of emulsification. A new start-up policy, validated by monitoring droplet formation at the membrane surface, was introduced that eliminated the non-uniformity in the size of droplets formed early during emulsification. The mechanisms contributing to droplet size distribution broadening at the membrane surface during formation were decoupled from those acting in the emulsification vessel during circulation. The high CV obtained at low PVA concentration and high agitation speed was attributed to drop breakup and coalescence occurring in the emulsification vessel, respectively, after droplets formed. The emulsification was followed by a shear-controlled suspension polymerisation to convert the discrete droplets of monomer to polymer beads. A wide range of reactor impeller speeds and PVA concentrations was studied to find the conditions under which the droplets formed via membrane emulsification would not undergo further break-up or coalesce during polymerisations and a one-to-one copy of the initial droplets with the same CV can be achieved.

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Preparation and characterization of poly(methyl methacrylate) beads

Holmes

Burford

Bertram

2008

J of Applied Polymer Sci

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For fluid-dynamic experiments involving concentrated suspensions and complex geometries, particles which are neutrally buoyant and which have the same refractive index as both the suspending fluid and the bounding container are needed. Poly(methyl methacrylate) (PMMA) particles can meet these requirements simultaneously. Therefore monodisperse beads with the refractive index and density of pure PMMA were needed. For comparison with particle migration theory, it is also important that bead size and sphericity be accurately controlled. In our fluid mechanics experiments, 500-lm diameter was required, a size where suspension polymerization is suitable. This article describes the controlled formation of PMMA beads in substantial quantities with desired size and a narrow particle size distribution. Reaction scale-up using a 2-L Bü chi reactor allowed batch yields of 200 g of PMMA beads with desired shape and size. However, microcavities reduced bead density and optical clarity.

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Characteristic intervals in suspension polymerisation reactors: An experimental and modelling study

Cited by 49 publications

References 34 publications

Liquid–liquid dispersion in a continuous oscillatory baffled reactor – Application to suspension polymerization

Liquid–liquid dispersion in a continuous oscillatory baffled reactor – Application to suspension polymerization

Uniform polymer beads by membrane emulsification-assisted suspension polymerisation

Preparation and characterization of poly(methyl methacrylate) beads

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