Monitoramento in situ e em tempo real de variáveis morfológicas do poli(cloreto de vinila) usando espectroscopia NIR

Faria, João Miguel de; Lima, Enrique Luis; Pinto, José Carlos; Machado, Fabricio

doi:10.1590/s0104-14282009000200005

Cited by 7 publications

(4 citation statements)

References 3 publications

(3 reference statements)

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“…The increase of the agitation speed leads to increase of rates of particle breakup and to shifting of the final particle size distribution toward smaller particle diameters . For this reason, the agitation speed is used for control of final average particle sizes in most industrial processes . Besides, the agitation speed is also important for minimization of fouling on reactor internals and proper control of heat transfer between the reacting system and the cooling fluid.…”

Section: Introductionmentioning

confidence: 99%

Effect of Agitation on Density of Poly(vinyl acetate) Particles Produced in Suspension Polymerization Reactions

Cordeiro

Peixoto

Oliveira

et al. 2014

Macro Reaction Engineering

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Poly(vinyl acetate) particles are produced through suspension polymerization reactions at different agitation speed. As expected, particle size distributions are strongly affected by the increasing speed of agitation. Surprisingly, the latter also causes the decrease of particle densities, which can be explained by encapsulation of small water droplets by the viscous reacting medium. Encapsulation of water droplets can lead to the formation of hollow particles that can be observed through microscopic analyses.

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Section: Introductionmentioning

confidence: 99%

Effect of Agitation on Density of Poly(vinyl acetate) Particles Produced in Suspension Polymerization Reactions

Cordeiro

Peixoto

Oliveira

et al. 2014

Macro Reaction Engineering

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“…No processo de polimerização em suspensão, o MVC é disperso na forma de gotas de diâmetro entre 50 e 250 µm (Faria Junior, 2008), em meio a uma fase aquosa contínua, por agitação vigorosa e na presença de um colóide protetor, também chamado dispersante ou agente de suspensão. Um iniciador solúvel no monômero é utilizado, de modo que a reação de polimerização ocorra dentro das gotas em suspensão, por um mecanismo de reações em cadeia via radicais livres.…”

Section: Produção Do Pvcunclassified

Tecnologias Para a Produção E Purificação Do PVC

Silva¹,

Góis²

2013

Revista CIATEC-UPF

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RESUMOO policloreto de vinila (PVC) é um dos mais importantes polímeros e pode ser produzido por alguns métodos, dentre os quais, a polimerização em emulsão, a polimerização em massa, a polimerização em solução e em suspensão. No processo de polimerização em suspensão, o mais utilizado, a conversão normalmente assume valores entre 83 e 90%. Sendo assim, faz-se necessário uma posterior purificação com o objetivo de aumentar ainda mais a pureza da suspensão ou lama de PVC. Além disso, o cloreto de vinila é um agente cancerígeno. Várias técnicas são empregadas para reduzir o teor do monômero de cloreto de vinilo (MVC) no PVC produzido, sendo possível classificar essas técnicas em duas categorias. Na primeira, que envolve métodos químicos, o monômero não reagido é induzido a reagir, gerando novos compostos que devem apresentar uma maior facilidade de remoção e ser não tóxicos, ou, até mesmo, menos voláteis do que o MVC. Já na segunda categoria, constituída por métodos físicos, o MVC é retirado do PVC por volatilização ou por extração com um solvente, ou, ainda, com o auxílio de uma resina de troca iônica. O objetivo desta revisão é apresentar as principais tecnologias de produção e purificação de PVC, uma vez que tais tecnologias, em especial as de remoção do MVC, são pouco conhecidas e divulgadas principalmente por meio de patentes de modo superficial. Palavras-chaves: Cloreto de vinila. Produção de PVC. Remoção de MVC. ABSTRACTPolyvinyl chloride (PVC) is a major commercial polymer and is widely used as a raw material in various chemical and petrochemical products. PVC resins are made commercially by some processes like the suspension, emulsion, mass and solution process. The convertion in the suspension process is about 83 to 93 percent so, is required to removal the vinyl chloride monomer (VCM) from PVC resin. Moreover vinyl chloride is a cancer causing agent. Various techniques are employed for reducing the VCM content of the PVC, and these techniques can be classified into two categories. The first, chemical method, the unreacted monomer is induced to react by generating new compounds. These compounds must be easily removed, nontoxic or even less volatile than VCM. In the second category, on the other hand, the VCM is removed from PVC by physical methods like volatilization or extraction with a solvent, or it is removed with the aid of an ion-exchange resin. The aim of this review is to present the main PVC production and purification technologies since these technologies are currently known by only a few research groups and some project officers. Besides, informations about PVC, specially about PVC purification technology generally are disclosed through patents that address the topic superficially.

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“…Several techniques have been developed since the second half of the twentieth century to study the bubbles/droplets/particle size distributions in heterogeneous systems (gas–liquid, liquid–liquid and solid–liquid) to understand and control the evolution of these distributions in chemical processes . These techniques are often based on laser spectroscopy, capillary spectroscopy , laser scattering , near‐infrared spectroscopy , and backscattered lighting .…”

Section: Introductionmentioning

confidence: 99%

On‐line monitoring of chord distributions in liquid–liquid dispersions and suspension polymerizations by using the focused beam reflectance measurement technique

Poblete

Castor

Nele

et al. 2015

Polymer Engineering & Sci

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The on-line monitoring of the droplet/particle size distributions is very important to ensure the quality and applicability of various products in heterogeneous systems. For this reason, the main objective of the present work was to study the usage of the focused beam reflectance measurement (FBRM) technique for monitoring of liquid-liquid dispersions (styrene dispersion in aqueous solutions) and suspension polymerization of styrene. To do better understand the FBRM technique in these systems, the effects of surfactant concentrations, agitation speed and ambient light were evaluated during the in-line monitoring of average chord lengths and chord-length distributions (CLD) at different operation conditions in batch experiments. In addition, a preliminary investigation of the optimal probe position was conducted in the polymerization experiments. It is shown that the FBRM technique is sensitive to variations of particle sizes in the characteristic ranges of particle diameters of typical styrene suspension polymerizations, being useful for monitoring and also control applications that require the on-line characterization of CLD in real time in liquid-liquid dispersions and polymerization systems. POLYM. ENG. SCI., 56:309-318, 2016.

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Monitoramento in situ e em tempo real de variáveis morfológicas do poli(cloreto de vinila) usando espectroscopia NIR

Cited by 7 publications

References 3 publications

Effect of Agitation on Density of Poly(vinyl acetate) Particles Produced in Suspension Polymerization Reactions

Effect of Agitation on Density of Poly(vinyl acetate) Particles Produced in Suspension Polymerization Reactions

Tecnologias Para a Produção E Purificação Do PVC

On‐line monitoring of chord distributions in liquid–liquid dispersions and suspension polymerizations by using the focused beam reflectance measurement technique

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