Influence of Stirring Speed on the Suspension Copolymerization of Styrene with Methyl Methacrylate

PRS 1 paraffin wax was encapsulated by means of suspension-like copolymerization of methyl methacrylate (MMA) with butyl acrylate (BA). The effects of the polymeric shell dry glass transition temperature (T g ) and the reaction temperature (T r ) were then studied. Additionally, the evolution of particle diameter, molecular weight, conversion, and T g during polymerization was also researched. The chemical properties of the shell material (acrylic polymer), together with those found in the core material (PRS 1 paraffin wax), for instance: polarity and interfacial tensions, largely determine whether the morphology of the microcapsules will be thermodynamically favored or not. The high polarity of MMA (c 0 ¼ 18 mN m 21 ) and BA (c 0 ¼ 24 mN m 21 ) should provide a thermodynamic driving force to cover the paraffin wax droplet which would result in a core/ shell thermodynamically favored structure. However, most systems are defined by kinetics rather than thermodynamics such as the monomers dry T g and T r . It was observed that penetration of polymer radical chains was severely limited when the dry T g was 108C above the reaction temperature, resulting in irregular and undifferentiated particles. However, penetration did occur when the copolymeric shell dry T g was 108C below the reaction temperature which led to uniform and spherical particles being synthesized. POLYM. ENG.

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“…, the system behavior analyzed corresponded to the latter. These results were previously reported by Cordoví et al and Sánchez et al .…”

Section: Resultssupporting

confidence: 92%

The effect of the dry glass transition temperature on the synthesis of paraffin microcapsules obtained by suspension-like polymerization

et al. 2013

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“…Number-average diameter, Sauter diameter, and weight final-average particle diameter are shown in Table I. At a stirring rate of 600 rpm, the diameter size is similar to the value obtained by the authors 11 for a vertical four-blade agitator. Higher stirring rates (Ͼ600) are expected to have no effect on the particle diameter, because the breakup of the individual drops is the controlling step for the droplets size during the polymerization process.…”

Section: Results With the Rushton Stirrermentioning

confidence: 66%

“…Small bumps in the model fittings, at about 180 min, are due to the corresponding jumps in the temperature profile that has been reported in a previous work. 11 Because the droplets size of the polymer is controlled by the conversion, a model able to reproduce experimental data as a function of the temperature and composition of the initial mixture is essential to obtain polymers with adequate properties.…”

Section: Reactor Simulationmentioning

confidence: 99%

“…The real temperature profile in the laboratory reactor was published in a previous work, 11 where the experimental procedure was established.…”

Section: Polymerization Proceduresmentioning

confidence: 99%

“…11 Essentially, styrene and methyl methacrylate were used free from the inhibitor. Polyvinylpirrolidone was used as dispersant agent in solution of 1 and 10% by weight to avoid drop coalescence in the samples.…”

Section: Experimental Materialsmentioning

confidence: 99%

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Development of a suspension copolymerization process for bone cement production

Cordoví

Lucas

Durán

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:Copolymers of MMA-STY with the suitable composition, particle size distribution, and molecular weight distribution for its medical application as bone cements have been obtained by means of suspension copolymerization. The influence of the stirring rate on the final mean particle size has been established, and the scale-up of the process has been performed with successful results. The application of a kinetic model allowed to estimate the copolymer composition during the process, which is essential to obtain polymers with adequate properties.

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