Butyl acrylate emulsion polymerization

The NIR-Raman spectroscopy was used by Wang et al. [163] to study the kinetics of styrene polymerizations in glass reaction flasks. Wang et al. [164], Ozpozan et al. [165], Al-Khanbashi et al. [166], Urlaub et al. [122], Bauer et al. [167], Van Den Brink et al. [168], McCaffery and Durant [169], and Elizalde et al. [170] performed similar studies forVA, styrene/butyl acrylate, MMA, cyanacrylate, styrene/ butadiene, styrene and butyl acrylate/MMA polymerizations in emulsion and miniemulsion reactions. These studies showed that NIR-Raman spectral data obtained in-line during emulsion polymerizations could be used for kinetic model building and kinetic analysis. 

Emulsion Polymerization. Emulsion polymerization is the most important industrial method for the preparation of acryhc polymers. The principal markets for aqueous dispersion polymers made by emulsion polymerization of acryhc esters are the paint, paper, adhesives, textile, floor pohsh, and leather industries, where they are used principally as coatings or binders. Copolymers of either ethyl acrylate or butyl acrylate with methyl methacrylate are most common. 

Bauer et al. describe the use of a noncontact probe coupled by fiber optics to an FT-Raman system to measure the percentage of dry extractibles and styrene monomer in a styrene/butadiene latex emulsion polymerization reaction using PLS models [201]. Elizalde et al. have examined the use of Raman spectroscopy to monitor the emulsion polymerization of n-butyl acrylate with methyl methacrylate under starved, or low monomer [202], and with high soUds-content [203] conditions. In both cases, models could be built to predict multiple properties, including solids content, residual monomer, and cumulative copolymer composition. Another study compared reaction calorimetry and Raman spectroscopy for monitoring n-butyl acrylate/methyl methacrylate and for vinyl acetate/butyl acrylate, under conditions of normal and instantaneous conversion [204], Both techniques performed well for normal conversion conditions and for overall conversion estimate, but Raman spectroscopy was better at estimating free monomer concentration and instantaneous conversion rate. However, the authors also point out that in certain situations, alternative techniques such as calorimetry can be cheaper, faster, and often easier to maintain accurate models for than Raman spectroscopy, hi a subsequent article, Elizalde et al. found that updating calibration models after... 

Product Identification was by GC/MS, NMR, and IR. Fundamental crosslinking chemistry was explored using swell measurements on simple solution copolymers and swell and tensile measurements with vinyl acetate (VAc), vinyl acetate/butyl acrylate (VAc/BA) or vinyl acetate/ethylene (VAE) emulsion copolymers. Polymer synthesis 1s described In a subsequent paper (6). Homopolymer Tg was measured by DSC on a sample polymerized In Isopropanol. Mechanistic studies were done 1n solution, usually at room temperature, with 1, 2 and the acetyl analogs 1, 2 (R =CH3). 

Emulsion Polymerizations, eg. vinyl acetate [VAc]/ABDA, VAc/ethylene [VAE]/ABDA, butyl acrylate [BA]/ABDA, were done under nitrogen using mixed anionic/nonlonic or nonionic surfactant systems with a redox Initiator, eg. t-butyl hydroperoxide plus sodium formaldehyde sulfoxylate. Base monomer addition was batch or batch plus delay comonomer additions were delay. 

Acrylic Elastomers. Acrylic elastomers possess good oil and heat resistance. They are made by polymerizing monomeric acid esters of ethyl or butyl acrylate and methoxyethyl acrylate or ethoxyethyl acrylate. They can be polymerized in emulsion, suspension, or solution systems (9) (see... 

ASA structural latexes have been synthesized in a two stage seeded emulsion polymerization. In the first stage, partially crosslinked poly(n-butyl acrylate) and poly( -butyl acrylate-sfaf-2-ethylhexyl acrylate) rubber cores are synthesized. In the second stage, a hard styrene acrylonitrile copolymer (SAN) shell is grafted onto the rubber seeds (16). 

Fig. 5. Dependence of the rate of polymerization [Rp/%Conv./min)] in the free-radical emulsion polymerization of butyl acrylate in the presence of PEO-MA macromonomer on emulsifier (E, p-nonyl phenol ethoxylate) concentration [100]. Temp. 50 °C...

In order to achieve the above objectives, three vinyl acrylic latexes of varying butyl acrylate content have been prepared and cleaned1 for use in the study. Several anionic and nonionic surfactants commonly usod in emulsion polymerization have been used to investigate the effects of surfactant structure and polymer composition on the solubilization process. Polarity of latex surface estimated from contact angle measurements have been used to study the effect of polymer polarity on surfactant adsorption. 

Emulsion Polymerization A typical recipe is give in Table I. Emulsion polymerization was carried out at 60°C under a nitrogen atmosphere using a batch process. Theoretical solids content in all the formulations was 25%, and generally the conversions were better than 98%. A polyvinyl acetate homopolymer and two poly (vinyl acetate-butyl acrylate) copolymers having VA/BA composition of 85/15 and 70/30 were prepared according to the above procedure. 

Four polymerization examples are presented here to illustrate both available sensitivity, experimental difficulties, and hopefully some interesting aspects of the polymerization processes. The first two examples are the semi-continuous emulsion polymerization of methyl methacrylate (MMA) and styrene, respectively. The third example is a batch charged copolymerization of butyl acrylate (BA) with MMA. The fourth example is a semi-continuous solution polymerization of an acrylic system. In this last example aliquots were taken manually and analyzed at 29.7°C under static conditions. No further polymerization occurred after the samples were cooled to this temperature. 

The cationic Surfmers produced much smaller particle sizes in the emulsion polymerization of styrene and styrene/butyl acrylate than the amphoterics (20-50 nm versus 100-300 nm). Some of the latter, however, conferred to the copolymer lattices stability to electrolytes and freeze-thaw [24]. Similar, but nonreactive surfactants produced from succinic anhydride gave similar stability but had much inferior water resistance [25]. 

The maleic Surfmers were tested in core-shell emulsion polymerization of styrene/butyl acrylate in comparison with a standard nonreactive surfactant (nonyl phenol reacted with 30 mol of EO - NP30). While the methacrylic-derived Surfmer was completely incorporated during the polymerization (although about one-third of it was buried inside the particles) the NP30, the maleic Surfmer and the allylic and vinyl Surfmers were not incorporated and could be extracted with acetone (for the last two probably because of the formation of acetone-extractable oligomers due to a chain transfer behavior) [31]. 

Recently Uniqema has introduced commercially a Surfmer under the trade name of Maxemul 5011. Maxemul is produced by esterification of an unsaturated fatty anhydride with a methoxy PEG such that the reactive group is close to the hydrophilic moiety [ 34 ]. Stable latexes with a solid content of 52% were produced in the seeded emulsion polymerization of film-forming methyl methacrylate/butyl acrylate/acrylic acid (3% Surfmer on monomers, constant monomer feeding rate over 4 h, potassium persulfate/sodium metabisulfate redox initiator). The latexes were stable to electrolytes but not to freeze-thaw. 

Schoonbrood, H.A.S., Unzue, MJ., Beck, O. and Asua, J.M. (1997) Reactive surfactants in heterophase polymerization. 7. Emulsion copolymerization mechanism involving three anionic polymerizable surfactants (surfmers) with styrene-butyl acrylate acrylic acid. Macromolecules, 30, 6024-33. 

Sindt, O., Gauthier, C., Hamaide, T. and Guyot, AJ. (2000) Reactive surfactants in heterophase polymerization. XVI. Emulsion copolymerization of styrene-butyl acrylate-acrylic acid in the presence of simple maleate reactive surfactants. /. Appl. Polym. Sci, 77,2768-76. 

This study illustrates a particular use of FT-Raman spectroscopy (Section 2.4.2) to monitor an emulsion polymerization of an acrylic/methacrylic copolymer. There are four reaction components to an emulsion polymerization water-immiscible monomer, water, initiator, and emulsifier. During the reaction process, the monomers become solubilized by the emulsifier. Polymerization reactions were carried using three monomers BA (butyl acrylate), MMA (methyl methacrylate), and AMA (allyl methacrylate). Figure 7-1 shows the FT-Raman spectra of the pure monomers, with the strong vC=C bands highlighted at 1,650 and 1,630 cm-1. The reaction was made at 74°C. As the polymerization proceeded, the disappearance of the C=C vibration could be followed, as illustrated in Fig. 7-2, which shows a plot of the concentration of the vC=C bonds in the emulsion with reaction time. After two hours of the monomer feed, 5% of the unreacted double bonds remained. As the... 

Some rather interesting, if complex, materials have been prepared by Vollmert (18). Previously we considered some of his materials composed of two polymers now we will consider mixtures of three or more polymers. (Notations relating to mode of polymerization and state of the polymer (14, 15) are omitted for clarity.) Because the individual polymers, in most cases, are multi-mer random copolymers in their own right, one monomer will be considered per polymer for simplicity in the following. In his example 5, the Vollmert emulsion polymerized 7i-butyl acrylate, styrene, 1,4-butanediol monoacrylate, and 1,4-butanediol... 

Recent progress in microelectronics has led to the construction of very sensitive instruments so that ever the concentration of active centres can be measured directly with increasing frequency. Lau et al. determined the stationary radical concentration in emulsion polymerizations of MMA, metha-crylic acid, and butyl acrylate by ESR. Thus k could be derived directly [134],... 

Unzueta et al. [18] derived a kinetic model for the emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) employing both the micellar and homogeneous nucleation mechanisms and introducing the radical absorption efficiency factor for micelles, F, and that for particles, Fp. They compared experimental results with model predictions, where they employed the values of Fp=10 and Fn,=10", respectively, as adjustable parameters. However, they did not explain the reason why the value of Fp, is an order of magnitude smaller than the value of Fp. Sayer et al. [19] proposed a kinetic model for continuous vinyl acetate (VAc) emulsion polymerization in a pulsed... 

In order to gain evidence for interfacial initiation, the redox initiator system was compared with a water-soluble initiator (VA-044) in terms of the emulsion polymerization behavior of butyl acrylate (BA)/[2-(methacryloyoxy)ethyl] trimethyl ammonium chloride (MAETAC). It was found that for the water-soluble initiator system, only homopoly(MAETAC) was formed and BA did not polymerize at all. In the case of VA-044, it was suggested that it may be difficult for polymeric free radicals in the aqueous phase to penetrate the viscous surfactant layer to initiate the polymerization of the BA monomer. On the other hand, it has also been found that BA could be rapidly polymerized under the same conditions if VA-044 is replaced with CHP/TEPA, indicating that radicals are formed in the interface, where they do not need to penetrate through viscous surfactant layer. 

Core-shell nanoparticles can also be fabricated using microemulsions. This was performed using a two-stage microemulsion polymerization beginning with a polystyrene seed [62]. Butyl acrylate was then added in a second step to yield a core-shell PS/PBA morphology. The small microlatex led to better mechanical properties than those of similar products produced by emulsion polymerization. Hollow polystyrene particles have also been produced by microemulsion polymerization of MMA in the core with crosslinking of styrene on the shell. After the synthesis of core-shell particles with crosslinked PS shells, the PMMA core was dissolved with methylene chloride [63]. The direct cross-... 

In contrast to the claims of the literature, vinyl ferrocene (available commercially) was found to be a very reactive monomer in the terpolymer system butyl acrylate/styrene/methacryllc acid. It was further found, again in contrast to the claims in the literature, that vinyl ferrocene could be emulsion polymerized via organic peroxide Redox catalysis. 

Some two stage emulsion graft copolymer materials synthesized and characterized by DMS include) the series poly (methyl methacrylate)/poly(n-butyl acrylate) (PMMA/ PnBA) synthesized by Dickie (14) and the series poly(ethyl methacrylate)/poly(n-butyl acrylate) (PEMA/PnBA) synthesized by Sperling et al. (1) The present study will continue the development of the PEMA/PnBA damping materials by incorporating a common comonomer) ethyl acrylate (EA)) in both stages of the emulsion polymerization. 

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