scholarly journals Mathematical Modeling of the Production of Elastomers by Emulsion Polymerization in Trains of Continuous Reactors

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1508
Author(s):  
Enrique Saldívar-Guerra ◽  
Ramiro Infante-Martínez ◽  
José María Islas-Manzur
Keyword(s):  
Emulsion Polymerization ◽  
Rate Coefficient ◽  
Mechanistic Model ◽  
A Priori ◽  
Particle Diameter ◽  
Styrene Butadiene Rubber ◽  
Copolymer Composition ◽  
Butadiene Rubber ◽  
Entry Rate ◽  
Monomer Composition

A mechanistic model is proposed to describe the emulsion polymerization processes for the production of styrene–butadiene rubber (SBR) and acrylonitrile–butadiene rubber (NBR) elastomers in trains of continuous stirred tank reactors (CSTRs). A single model was used to describe both processes by choosing the proper physicochemical parameters of each system. Most of these parameters were taken from literature sources or estimated a priori; only one parameter (the entry rate coefficient) was used as an adjustable value to reproduce the kinetics (mainly conversion), and another parameter (the transfer to polymer rate coefficient) was used to fit the molecular weight distribution (MWD) experimental values from plant data. A 0-1-2 model for the number of particles and for the moments of the MWD was used to represent with more fidelity the compartmentalization effects. The model was based on approaches used in previous emulsion polymerization models published in the literature, with the premise of reaching a compromise between the level of detail, complexity, and practical value. The model outputs along the reactor train included conversion, remaining monomer composition, instantaneous and accumulated copolymer composition, the number of latex particles and particle diameter, polymerization rate, the average number of radicals per particle, average molecular weights, and the number of branches per chain.

scholarly journals Styrene-Butadiene Rubber by Miniemulsion Polymerization Using In Situ Generated Surfactant

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1476
Author(s):  
Anderson M. S. Medeiros ◽  
Elodie Bourgeat-Lami ◽  
Timothy F. L. McKenna
Keyword(s):  
Particle Diameter ◽  
Weight Ratio ◽  
Miniemulsion Polymerization ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Secondary Nucleation ◽  
Potassium Oleate ◽  
Solids Content ◽  
Styrene Butadiene

An alternative approach for the synthesis of styrene butadiene rubber (SBR) copolymer latexes was explored in order to obtain low gel fractions and high solid contents. The ultra-turrax-assisted miniemulsion stabilized by in situ surfactant generation was adopted as the main strategy since this technique can inhibit the eventual presence of secondary nucleation producing polybutadiene particles and also control the cross-linking degree. Styrene monomer was first miniemulsified using an ultra-turrax and in situ generated surfactant using either hexadecane (HD) or octadecyl acrylate (ODA) as the hydrophobe. Dynamic light scattering (DLS) measurements of droplet size indicated faster stabilization and the production of smaller droplet diameters ca. 190 nm (PdI = 0.08) when employing in situ generated potassium oleate (K-Oleate) in comparison to SDS-based miniemulsions. High butadiene-level SBR latexes with ca. 50% solids content, a glass transition temperature (Tg) of −52 °C, and a butadiene to styrene weight ratio of 75:25, were then obtained using the miniemulsion droplets as seeds. Turbiscan and DLS measurements revealed a very stable resulting latex with SBR particle diameter of ca. 220 nm and a low polydispersity index (PdI). Secondary nucleation was prevented as indicated by the low Np/Nd value. Cryo-TEM images showed a narrow distribution of particle size as well as the absence of agglomeration. The gel content was below 10% when tert-dodecyl mercaptan (t-DM) was used as chain transfer agent (CTA).

Polymer-Fraction Dependence of Entry Rate Coefficients in Emulsion Polymerization

1992 ◽  
Vol 45 (12) ◽  
pp. 2057 ◽  
Author(s):  
GL Leslie ◽  
DH Napper ◽  
RG Gilbert
Keyword(s):  
Emulsion Polymerization ◽  
Aqueous Phase ◽  
Rate Coefficient ◽  
Monomer Concentration ◽  
Weight Fraction ◽  
Rate Coefficients ◽  
Seeded Emulsion Polymerization ◽  
Entry Rate ◽  
Initiator Efficiency ◽  
Approach To Steady State

Data on the rate of approach to steady state in a series of studies of the seeded emulsion polymerization of styrene yield the dependence of the rate coefficient for entry of free radicals into latex particles as a function of the weight-fraction polymer and hence of monomer concentration in the aqueous phase. The results are in accord with a model for the entry process (i.e., for the initiator efficiency) based on aqueous-phase propagation and termination being the rate-controlling events.

Reflections on the Past and Future of Polyether Elastomers and on Redox Emulsion Polymerization

1991 ◽  
Vol 64 (3) ◽  
pp. 56-64 ◽  
Author(s):  
E. J. Vandenberg
Keyword(s):  
Emulsion Polymerization ◽  
American Chemical Society ◽  
Chemical Society ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Polymer Science ◽  
The Past ◽  
Synthetic Rubber ◽  
Styrene Butadiene ◽  
To Receive

Abstract I am greatly honored to have been selected to receive the prestigious Charles Goodyear Medal of the Rubber Division of the American Chemical Society. My work in the rubber field falls into two general areas: (1) early discoveries on the redox emulsion polymerization of styrene-butadiene rubber (SBR) and (2) polyether elastomers. I am perhaps best known for my work on polyether elastomers since I discovered, patented, and helped develop several families of polyether elastomers which were commercialized and are still important speciality elastomers. Most of my talk will be in that area. However, my SBR studies included my first important polymer-science discovery and preceded those who independently discovered the same systems and who were able to develop them commercially to the considerable advantage of our largest volume synthetic rubber, SBR. After briefly reviewing these past areas, I will give you my reflections on what important future developments for the rubber field could arise in the polyether area.

scholarly journals Study of Carbon Black Types in SBR Rubber: Mechanical and Vibration Damping Properties

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2394
Author(s):  
Marek Pöschl ◽  
Martin Vašina ◽  
Petr Zádrapa ◽  
Dagmar Měřínská ◽  
Milan Žaludek
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Mechanical Energy ◽  
Mechanical Vibration ◽  
Particle Diameter ◽  
Vibration Damping ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Damping Properties ◽  
Rubber Composites

Styrene–butadiene rubber mixtures with four types of carbon black were studied in this paper. The mechanical properties, including the ability to damp mechanical vibration, were investigated, along with dynamical mechanical analysis (DMA). It has been found that carbon black types N 110 and N 330, having the largest specific surface area and the smallest particle diameter, provide a good stiffening effect. These particles have significant interactions between the rubber, resulting in good reinforcement. On the other hand, the carbon black N 990 type has a lower reinforcing effect and improved vibration damping properties at higher excitation frequencies due to higher dissipation of mechanical energy into heat under dynamic loading. The effect of the number of loading cycles on vibration damping properties of the rubber composites was also investigated in this study. It can be concluded that the abovementioned properties of the investigated rubber composites correspond to physical–mechanical properties of the applied carbon black types.

Molecular Weight Control of Elastomers Prepared by Emulsion Polymerization

1976 ◽  
Vol 49 (3) ◽  
pp. 610-649 ◽  
Author(s):  
C. A. Uraneck
Keyword(s):  
Molecular Weight ◽  
Emulsion Polymerization ◽  
Weight Control ◽  
Experimental Studies ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Emulsion Systems ◽  
Commercial Polymers ◽  
Styrene Butadiene

Abstract Control of molecular weight is a prerequisite for the production of commercial polymers. This is especially true of elastomers for which satisfactory processing is either an implied or a formal specification. This review covers the theories and their applications for the control of molecular weights for the production of styrene-butadiene rubber (SBR), emulsion butadiene rubber (E-BR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), acrylic-butadiene rubber (ABR), and acrylic rubber. The complexity of the emulsion polymerization system is reflected in the large number of experimental and theoretical studies. Chronologically the theories and experiments based on the original mechanism proposed by Harkins and on the quantitative hypothesis of Smith and Ewart evolved into numerous publications. These works have been periodically reviewed, and several recent reviews give detailed descriptions of these studies. A review by Alexander and Napper, although subjective in choice of papers examined, presents a critical analysis of the major theories of emulsion polymerization systems. However, none of the reviews just cited cover in a significant way the control of the molecular weight of polymers prepared in the presence of reactive transfer agents. The theoretical and experimental studies of the control of molecular weight of elastomers prepared in emulsion systems came from a series of studies different from those concerned solely with emulsion theory and mechanism. In this review the broad features of the mechanism first proposed by Harkins and the hypothesis of Smith and Ewart are accepted. The derivation of modifier depletion and molecular weight equations and the calculation of the theoretical curves used in emulsion systems for the preparation of elastomers are presented next.

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