Emulsion Copolymerisation

Ion-exchange packing materials are traditionally formed from the emulsion copolymerisation of styrene and divinylbenzene, the latter polymer is used to provide cross linking and thus increase the rigidity of the beads. Ionic functional groups are chemically bonded to this backbone. Pellicular silica-based packing materials may also be used which are then coated with a synthetic ion-exchange resin but these tend to have comparatively less sample capacity. 

N. J. Earhart, The Grafting Reactions ofPoby(vinyl alcohol) During the Emulsion Copolymerisation of Poly(vinyl acetate-co-butyl acrylate), Ph.D. dissertation. 

These are generally manufactured by the emulsion copolymerisation process. The commercially available nitrile rubbers differ from one another in three aspects acrylonitrile content, polymerisation temperature and mooney viscosity. The content of acrylonitrile has a profound effect on the properties of vulcanised nitrile rubber, influencing its resistance to oils and fuels. 

A very simple method to obtain polymeric dispersions in liquid polyethers is to make a mixture between a polyether polyol and a polymeric latex, such as the azeotropic copolymer styrene - ACN (StACN copolymer), obtained by emulsion copolymerisation, having around 20-40% solid content. The water is eliminated step-by-step by vacuum... 

Kramer,S. (2005) Heat Balance Calorimetry and Multirate State Estimation Applied to Semibatch Emulsion Copolymerisation to Achieve Optimal Control. PhD Thesis, University of Dortmund. 

Polyurethane acrylate (PU-A) containing a double bond and COOH group was synthesised by the stepwise reaction of TDI, polyetherdiol, dimethylolpropionic acid (DMPA) and 2-hydroxypropyl acrylate (HPA). The PU-A was neutralised with triethylamine and self-emulsified in water to form the PU-A emulsion seed. The seeded emulsion copolymerisation of methyl methacrylate (MMA) onto the PU-A seed was carried out at 80C under soap-free conditions and an anionic latex of P(UA-MMA) was obtained. The structure of the P(UA-MMA) copolymer, its latex properties and the cast film were significantly affected by the amounts of HPA, DMPA and MMA. The results were discussed. 21 refs. 

SiUcone-modified styrene-butyl acrylate copolymer latex was synthesised by emulsion copolymerisation using octamethylcyclotetrasiloxane(D4), styrene and butyl acrylate as raw materials, potassium persulphate as initiator and propylmethacrylate triethoxysilane as crosslinking agent. The IR spectroscopic studies showed that the vinyl monomers were completely copolymerised with D4. The prepared silicone-modified copolymer latex with the IPNs tended to have higher stability and better toluene and water resistance than styrene-butyl acrylate copolymer latex. The glossiness of coated paper was improved with silicone-modified copolymer latex and it was at a maximum when D4 was about 3% of total monomers. 16 refs. 

Details are given of the preparation of model ethyl acrylate-methacrylic acid copolymer latices by non-seeded semicontinuous emulsion copolymerisation. Polydispersity was examined using dynamic and static light scattering. Correlations between hydrodynamic volume and viscosity properties of the dispersions are discussed. The different character of the particle structure was confirmed by differences in particle disintegration after alkali addition or in the presence of methanol. 19 refs. 

Development of optimal strategies for the emulsion copolymerisation of vinyl acetate and VeoVa 10 has been carried out. These strategies are based on a hybrid mathematical model for the process that includes rigorous material and energy balances and empirical equations for uncertain terms. The strategies were implemented in a laboratory-scale calorimetric reactor. 32 refs. 

The results are reported of a study of the mechanism of stabilisation during vinyl acetate-ethylene emulsion copolymerisation using various colloidal stabilisers. These stabilisers included PVAl, aUcylphenol ethoxylate and a diisocyanate chain extended polyethylene glycol. The effects of these stabilisers on emulsion characteristics, film properties and applications behaviour are discussed. 5 refs. (217th ACS National Meeting, Anaheim, Calif., 21-25 March, 1999)... 

The application of ultrasonics to the monitoring of emulsion polymerisation reactors is considered. The use of acoustic speed measurements to monitor conversion is demonstrated by its apphcation to the control of the emulsion copolymerisation of styrene and butyl acrylate. The potential of acoustic attenuation for the measurement of particle size is discussed and applied to the determination of the particle size distribution of PVC and PTFE latices. 27 refs. 

Polymerisable styrenic surfactants (surfmers) and non-reactive analogues were applied in emulsion copolymerisation of acrylic monomers in a seeded semi-... 

FUNCTIONAL POLYMERS. I.xni. EMULSION COPOLYMERISATION OF MALEIMIDE TYPE MONOMERS WITH ACRYLONITRILE AND STYRENE IN ABS LATEXES Bartus J Simonsick W J Vogl O Brooklyn,Polytechnic University DuPont de Nemours E.I., Co.Inc. 

Latex particles bearing carbohydrate species were prepared by emulsion copolymerisation of styrene or methyl methacrylate with polymerisable liposacchaiide surfactants. Surface active and mesomorphic properties are discussed. Data are given concerning the adsorption of bovine serum albumin and the covalent binding of antibodies and singlestrand DNA fragments on their surface. 27 refs. 

The composition and quantity of styrene-maleic anhydride (SMA) copolymer resins were varied in emulsion copolymerisation of methyl methacrylate and n-butyl acrylate conducted by both batch and semicontinuous processes. The resulting particle sizes and levels of coagulum were measured to determine the optimum conditions for incorporation of the SMA resins into the resulting latexes. A semicontinuous process, in which no buffer was included and the SMA was added in a second stage comonomer emulsion, was found to produce coagulum-free latexes. 13 refs. 

EMULSIFIER-FREE EMULSION COPOLYMERISATION OF STYRENE WITH TWO DIFFERENT AMINO-CONTAINING CATIONIC MONOMERS. II. SURFACE AND COLLOIDAL CHARACTERISATION Sauzedde F Ganachaud F Elaissari A Pichot C Lyon,Ecole Nationale Superieure... 

A series of multi-hollow structure core-shell latex particles in the presence and absence of acrylic acid was synthesised by seeded emulsion copolymerisation, then... 

Methyl methacrylate-butyl acrylate copolymer latex particles were synthesised by both seeded and unseeded semicontinuous emulsion copolymerisation. Particle size and surface charge densities were characterised by TEM and potentiometric and conductimetric titrations. An investigation of the effect of surface density on zeta-potential is described. 18 refs. 

EMULSION COPOLYMERISATION LATICES FOR INTERIOR AND EXTERIOR COATINGS Ayonb M M H... 

European Polymer Journal 32, No.9, Sept. 1996, p. 1139-43 KINETIC STUDIES ON EMULSION COPOLYMERISATION OF VINYLACETATE AND ACRYLICS IN THE BATCH PROCESS Tang L-G Weng Z-X Pan Z-R Hangzhou,Zhejiang University... 

The batch emulsion copolymerisation of vinyl acetate and acrylic acid, methyl acrylate and acrylamide was investigated at 25C with a redox initiator system and a complex emulsifier. The kinetic behaviour of the copolymerisation and the structure of the resulting copolymers, as well as the particle size and number density of the latexes, were studied as a function of the conversion and the reaction time. 10 refs. 

Waterborne resins for surface coatings are not only prepared by an emulsion copolymerisation technique. They can be prepared using a solution technique with a water soluble organic solvent, or in water. This is the least common. 

A special aspect of (emulsion) copolymerisation compared to (emulsion) homopolymerisation is the occurrence of composition drift. In combination with the instantaneous heterogeneity (statistical broadening around the average chemical composition), this phenomenon is responsible for the chemical heterogeneity of the copolymers formed. Composition drift is a consequence of the difference between instantaneous copolymer composition and overall monomer feed composition. This difference is determined by (a) the reactivity ratios of the monomers (kinetics) and (b) the monomer ratio in the main loci of polymerisation (viz., latex particles) that can differ from the overall monomer ratio of the feed (as added according to the recipe), which in turn is caused by monomer... 

In order to be able to describe and control an emulsion copolymerisation, both the reactivity ratios and monomer partitioning have to be known. 

Ternary emulsion copolymerisation. In the fundamental investigations described in literature dealing with emulsion copolymerisation most attention has been given to binary copolymerisation, that is, polymerisation of two monomers. Far less attention has been paid to ternary emulsion copolymerisation (three monomers), that is, terpolymerisation. Emulsion terpolymerisation investigations, mostly dealing with properties and applications, have been published mainly in the patent literature. 

It is obvious that the typical aspects that distinguish emulsion copolymerisation from homopolymerisation, for example, monomer partitioning, dependence of kinetics on the local monomer concentration ratio etc., become much more complex when three monomers are involved, not to mention the complications in terpolymer analysis. 

However, since it can easilybe understood that using three monomers gives the possibility to obtain an even larger variety and refinement of copolymer properties, there is considerable research on emulsion terpolymerisation, although it is to be expected that there will be little or no fundamental mechanistic differences between binary and ternary emulsion copolymerisation systems. 

The ultimate goal of most of the investigations on emulsion copolymerisation is to be able to control the process in such a way as to produce a copolymer product (latex or coagulate) with desired properties. For this purpose the semi-continuous (sometimes called semi-batch) emulsion copolymerisation process is widely used in industry. The main advantages of this process as compared with conventional emulsion batch processes include a convenient control of emulsion polymerisation rate in relation with heat removal and control of chemical composition of the copolymer and particle morphology. These are important features in the preparation of speciality or high performance polymer latexes. 

Semi-continuous emulsion copolymerisation processes can be performed by applying various monomer addition strategies. 

For instance, this procedure is followed in manypapers dealing with the semi-continuous emulsion copolymerisation of vinyl acetate and butyl acrylate (e.g. El-Aasser et al, 1983). Two main situations can be distinguished with respect to the monomer addition rate, (a) Flooded conditions the addition rate is higher than the polymerisation rate, (b) Starved conditions the monomers are added at a rate lower than the maximum attainable polymerisation rate (if more monomers were to be present). The latter process (starved conditions) is often applied in the preparation of homogeneous copolymers/latex particles. In this case after some time during the reaction, because of the low addition rates, a steady state is attained in which the polymerisation rate of each monomer is equal to its addition rate and a copolymer is made with a chemical composition identical to that of the monomer... 

Van Doremaele (1990) applied a more pragmatic approach a method which can be applied without actually calculating n t) or n(fp) and may therefore be more generally applicable. This method was applied to the emulsion copolymerisation of styrene (S) and methyl acrylate (MA). The batch emulsion copolymerisation of S and MA is known to often produce highly heterogeneous copolymers (styrene being the more reactive and less water-soluble monomer). 

In many cases latex products are composed of more than one monomer. In copolymerisation two or more monomers are built-in into the polymer chains. The copolymer chains are produced by simultaneous polymerisation of two or more monomers in emulsion. Emulsion copolymerisation allows the production of materials with properties which cannot be obtained by latex products consisting of one monomer, that is, homopolymer latexes, or by blending homopolymers. The properties of the materials required are usually dictated by the market. Nowadays, most of the material properties are achieved by combination of more than two monomers in the copolymer product. Typical industrial emulsion polymerisation formulations are mixtures of monomers giving hard polymers, and monomers leading to soft polymers. Styrene and methyl methacrylate are examples of monomers giving hard polymers, that is, polymers with a high glass transition temperature, Tg. Soft polymers, that is, polymers with a low Tg, are, for example, formed from -butyl acrylate. The industrial emulsion polymerisation formulations also contain small amounts of functional monomers such as acrylic and methacrylic acid to impart improved or special characteristics to the latex product. Note that the colloidal stability of the latex product can be seriously improved by acrylic and methacrylic acid. Furthermore, some applications may demand for the addition of other specialty monomers that make the kinetics of the copolymerisation even more complex. 

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