Styrene-butadiene latex, preparation

Parker et al. [49] altered the stabilization mechanism for styrene-butadiene latex prepared by emulsion polymerization from anionic to cationic so that they could get a spontaneous flocculation with aqueous montmorillonite slurry and the latex. Evaluation of the rubber nanocomposite prepared in this manner gave dramatic increases in modulus, strength, percent elongation, and decrease in hysteresis. 

For the purposes of the F EI Guide a process unit is defined as any primary item of process equipment. For example, in the process area of a styrene/butadiene latex plant, process units could include monomer mix feed preparation, reactors, stripppers, monomer recovery, aqueous room, and styrene scrubber. A warehouse also may be treated as a process unit. In particular, materials stored within a fire-walled area, or within the total storage area where fire walls are not provided, would constitute such a process unit. 

Table IV shows that dialysis is ineffective in cleaning the latexes for characterization. Earlier work (3,5) also showed that dialysis is ineffective in removing the adsorbed emulsifier and replacing the Na+ and K counterions with H ions. Others have also found that dialysis does not remove emulsifier completely. Brodnyan and Kelley (10) found that aqueous solutions of C14-tagged sodium lauryl sulfate equilibrated upon dialysis, but only 9.5% and 22% of the emulsifier was removed from latexes dialyzed under the same conditions. Matijevic et al. (11) dialyzed a butadiene-styrene copolymer latex prepared using rosin acid soap for 160 days and removed only about 50% of the emulsifier.

It has been proved that incorporation of carboxylic acid groups in the polymeric chain has a significant effect on colloidal properties of latex, processability, and end-use property. Carboxylated styrene-butadiene latexes (XSBR) are prepared via batch emulsion copolymerization with different amounts of acrylic acid in the absence of emulsifier. They are among the most important polymeric colloids, and can be used as binder in paper coatings, carpet backing, paints, and nonwoven. There are several studies on the preparation and properties of XSBR latexes. 

Styrene-butadiene copolymers are extremely important to the rubber industry. They are particularly important in tire manufacture. Styrene-butadiene polymer is produced by emulsion polymerization and solution polymerization. Most of the volume is by emulsion polymerization. This affords the opportunity to prepare polymer nanocomposites by several avenues. One can blend an aqueous dispersion of the nanoparticles with the styrene-butadiene latex before flocculation to produce the rubber crumb, disperse an organically treated nanoparticle in the styrene-butadiene solution polymer before the solvent is stripped from the polymer, disperse the organically treated nanoparticles into the monomers, or prepare the rubber nanocomposite in the traditional compounding approach. One finds all of these approaches in the literature. One also finds functional modifications of the styrene-butadiene polymer in the literature designed to improve the efficiency of the dispersion and interaction of the nanoparticles with the polymer. 

Only limited success has been achieved in compounding organomontmoriUonites with styrene—butadiene rubber to prepare rubber nanocomposites [51], Knudson et al. [51] discovered that flocculation of the aqueous blend of styrene-butadiene latex and montmorOlrMiite gives an exfoliated clay-rubber nanocomposite. The approach offers the most convenient and effective method for the preparation of clay-styrene-butadiene rubber nanocomposites. 

Almost all synthetic binders are prepared by an emulsion polymerization process and are suppHed as latexes which consist of 48—52 wt % polymer dispersed in water (101). The largest-volume binder is styrene—butadiene copolymer [9003-55-8] (SBR) latex. Most SBRlatexes are carboxylated, ie, they contain copolymerized acidic monomers. Other latex binders are based on poly(vinyl acetate) [9003-20-7] and on polymers of acrylate esters. Poly(vinyl alcohol) is a water-soluble, synthetic biader which is prepared by the hydrolysis of poly(viayl acetate) (see Latex technology Vinyl polymers). 

Butadiene copolymers are mainly prepared to yield mbbers (see Styrene-butadiene rubber). Many commercially significant latex paints are based on styrene—butadiene copolymers (see Coatings Paint). In latex paint the weight ratio S B is usually 60 40 with high conversion. Most of the block copolymers prepared by anionic catalysts, eg, butyUithium, are also elastomers. However, some of these block copolymers are thermoplastic mbbers, which behave like cross-linked mbbers at room temperature but show regular thermoplastic flow at elevated temperatures (45,46). Diblock (styrene—butadiene (SB)) and triblock (styrene—butadiene—styrene (SBS)) copolymers are commercially available. Typically, they are blended with PS to achieve a desirable property, eg, improved clarity/flexibiHty (see Polymerblends) (46). These block copolymers represent a class of new and interesting polymeric materials (47,48). Of particular interest are their morphologies (49—52), solution properties (53,54), and mechanical behavior (55,56). 

A bond coat of a polymer latex (also called polymer emulsions or dispersions) such as styrene butadiene (SBR), polyvinyl acetate (PVA) acrylics or modified acrylics. These are applied to the prepared concrete as... 

A modified latex composition contains a phosphorus surface group. Such a latex is formed by emulsion polymerization of unsaturated synthetic monomers in the presence of a phosponate or a phosphate which is intimately bound to the surface of the latex. Thus, a modified latex containing 46% solids was prepared by emulsion polymerization of butadiene, styrene, acrylic acid-styrene seed latex, and a phosphonate comonomer in H20 in the presence of phosphated alkylphenol ethoxylate at 90°C. The modified latex is useful as a coating for substrates and as a binder in aqueous systems containing inorganic fillers employed in paper coatings, carpet backings, and wallboards [119]. 

The formation of coagulum is observed in all types of emulsion polymers (i) synthetic rubber latexes such as butadiene-styrene, acrylonitrile-butadiene, and butadiene-styrene-vinyl pyridine copolymers as well as polybutadiene, polychloroprene, and polyisoprene (ii) coatings latexes such as styrene-butadiene, acrylate ester, vinyl acetate, vinyl chloride, and ethylene copolymers (iii) plastisol resins such as polyvinyl chloride (iv) specialty latexes such as polyethylene, polytetrafluoroethylene, and other fluorinated polymers (v) inverse latexes of polyacrylamide and other water-soluble polymers prepared by inverse emulsion polymerization. There are no major latex classes produced by emulsion polymerization that are completely free of coagulum formation during or after polymerization. 

Bradford and Vanderhoff (20) have also prepared films from crosslinked latex particles. These authors studied a 65 35 styrene-butadiene copolymer crosslinked with varying amounts of divinylbenzene and found that although the incorporation of divinylbenzene retarded the coalescence of latex particles, these particles did indeed coalesce, presumably due to a similar interdiffusion of polymer chain ends. 

Identification Identify emulsion-polymerized Butadiene-Styrene Rubber latex and solid by comparing their infrared absorption spectra with the respective four typical spectra as shown in the section on Infrared Spectra. Prepare latex samples by first drying them at 105° for 4 h, then by dissolving them in hot toluene and evaporating on a potassium bromide plate. Prepare solid samples by dissolving them in hot toluene and evaporating on a potassium bromide plate. 

After the paper making process is complete, latexes that are useful as binders for the application of clays or CaCC>3 to paper for printing paper may be prepared using the dimer of AMS. In a typical formulation, styrene, butadiene, Me methacrylate, and acrylonitrile were emulsion polymerized in the presence of AMS dimer to obtain a copolymer latex.473 Surprisingly, the AMS dimer was used in combination with tert-dodecylmercaptan, so there may have been some residual odor. Unsaturated carboxylic acids, such as acrylic acid, or sulfonic acids, such as 2-ethylsulfonyl acrylate, or unsaturated amides, such as acrylamide, are also useful, providing the polarity necessary in these applications.474... 

Mn 2 to 4). In olefin polymerization as well as CO copolymerization, a Umited conversion of liquid 1-olefin (co)monomers is yet to be overcome in many cases. As an example of properties that could find potential appUcation, polyolefins contain a negligible proportion of double bonds by comparison to styrene-butadiene copolymers, a hydrocarbon polymer currently prepared by free-radical emulsion polymerization on a large scale. This can result in a considerably higher stability towards UV-Ught and air of polymer films formed from polyolefin latexes. 

Materials. Styrene-Butadiene Rubber (SBR) Latex. SBR latex was prepared by redox emulsion polymerization using (in parts) butadiene (69) and styrene (31) at 6°-40°C (pinane hydroperoxide/sodium formaldehyde sulfoxylate/Fe++ as initiator) in the presence of potassium oleate (2.7) inorganic electrolytes (0.45) as polymerization aids, and demineralized water (135) until a conversion of 70% was achieved. Residual monomers were then removed. 

Carboxylic Styrene-Butadiene (SB) Latex. The carboxylic latex was prepared by emulsion polymerization at 60°C using (in parts) butadiene (40), styrene (57.5), and acrylic acid (2.5) in the presence of demineralized water (138), 14C-sulfonate (0.5) as emulsifier, and tertiary dodecyl mercaptan (0.5) and ammonium persulfate (0.5) as initiator. 

Witt [1959] studied under vacuum gamma-radi-ation-induced crosslinking in butadiene-styrene copolymers, homopolymers and mixtures of these homopolymers, (Table 11.9). The behavior of the styrene units in the copolymers and in the physical mixtures, was different. Gel fraction measurements showed that in the copolymer, the styrene units did inhibit the crosslinking of the polybutadiene. However, there was no evidence of such inhibition in the mill- and latex-prepared physical mixtures of the two homopolymers. 

This chapter concludes with brief reference to carboxylated rubber latexes. Further information, with references, is available in a review by Blackley [27]. Carboxylated rubber latexes contain rubbery polymers which have been modified by inclusion of a small amount of a copolymerisable carboxylic-acid monomer in the emulsion polymerization system by which they were prepared. Typical carboxylic-acid monomers are acrylic acid (XI), methacrylic acid (XII) and itaconic acid (XIII). The most industrially-important rubber latexes of this type are the carboxylated styrene-butadiene rubber latexes. Also of considerable... 

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