Latex solution

Poly(vinyl acetate) and its copolymers with ethylene are available as spray-dried emulsion soHds with average particle sizes of 2—20 p.m the product can be reconstituted to an emulsion by addition of water or it can be added directly to formulations, eg, concrete. The powders may be used to raise soHds of a lower soHds latex. Solutions of resin in methyl and ethyl alcohol at 2—50 wt % soHds are also available. 

Rubber latex cement Rubber latex cement consists of mixtures of sand and other fillers which are gauged with rubber latex solution. These cements are suitable for dilute acid conditions and are particularly useful in conditions where dilute acid alternates with water or dilute alkalis. They remain very slightly resilient and adhere very well to stoneware. They are not of course... 

Exclusion Chromatography Analysis of Latex Solutions for Monitoring Nitrile Resin Polymerizations... 

Two different emulsion polymerization reactions were Investigated. One was the polymerization of acrylonitrile and methylacrylate (75/25 AN/MA) In the presence of an acrylonitrile elastomer (70/30 BD/AN) to produce a graft resin, llie second was the copolymerization oiE acrylonitrile and styrene (70/30 AN/S). Chromatographic analyses of latex solutions were conducted periodically during both types of polymerization reactions, using acetonitrile as latex solvent and chromatographic mobile phase. 

Latex solutions for chromatographic analysis were prepared by adding weighed amounts of latex to known amounts of acetonitrile. Latex solution concentrations were 0. 2 g/100 ml for AN/S copolymers and 1. 0 g/100 ml for the AN/MA graft resins. 

The latex solutions were filtered through a 0. 9 pm filter prior to chromatographic analysis. Known volumes of the filtered solutions were injected into the chromatograph by loop injection. Injection volumes were 250 pi of AN/M solutions and 500 pi of AN/S solutions. 

Overall goal of this work was to maximize the amount of information obtained from chromatographic analysis of latex solutions. More specific aims were (1) measure amounts of unreacted monomers, as one measure of conversion, (2) determine amount of polymer, as a second measure of conversion, (3) estimate chemical composition of the polymer formed, and (4) look for evidence of grafting (in the AN/M polymerization) as evidenced by detection of insoluble polymer formation. 

Ability to analyze unreacted monomers was dependent on detector selectivity. The UV detector was operated at 254 nm for analysis of AN/S latex solutions. Styrene is a strong UV abosrber at this wavelength while acrylonitrile has no measurable absorbance at 254 nm. Thus, the UV detector was entirely selective to monomeric styrene. The refractometer detector was sensitive to both acrylonitrile and styrene when each was present in the desired copolymer proportions (70/30). However,... 

Unreacted monomers In AN/M latex solutions were measured similarly. Methylacrylate Is a relatively strong UV absorber In the 225-250 nm range while acrylonitrile does not significantly absorb UV radiation at wavelengths above about 220 nm. At 230 nm, the wavelength used, the UV detector responded only to methylacrylate. And the refractive Indices of the two monomers are such that. In the 75/25 AN/MA proportions used, the refrac-tometer was Insensitive to methylacrylate. The reiErac tome ter therefore functioned as a selective detector for acrylonitrile In the presence of methylacrylate. 

The quality of the water used in emulsion polymerization affects the manufacture of ESBR. Water hardness and other ionic content can directly affect the chemical and mechanical stability of the polymer emulsion (latex). Solution polymerization can use various solvents, primarily aliphatic and aromatic hydrocarbons, SSBR polymerization depends on recovery and reuse of the solvent for economical operation as well as operation under the air-quality permitting of the local, state, and federal mandates involved,... 

Figure 6.5 Ultrafiltration flux as a function of time of an electrocoat paint latex solution. Because of fouling, the flux declines over a period of days. Periodic cleaning is required to maintain high fluxes [14]. Reprinted from R. Walker, Recent Developments in Ultrafiltration of Electrocoat Paint, Electrocoat 82, 16 (1982) with permission from Gardner Publications, Inc., Cincinnati, OH...

A series of experimental results obtained with latex solutions illustrating the effect of concentration and pressure on flux are shown in Figure 6.8. The point at which the flux reaches a plateau value depends on the concentration of the latex in the solution the more concentrated the solution, the lower the plateau flux. The exact relationship between the maximum flux and solute concentration can be obtained by rearranging Equation (6.2) to obtain... 

Plots of the limiting flux. /mux as a function of solution concentration for latex solution data are shown in Figure 6.9 for a series of latex solutions at various feed solution flow rates. A series of straight line plots is obtained, and these extrapolate to the gel concentration cgel at zero flux. The slopes of the plots in Figure 6.9 are proportional to the term D/S in Equation (6.3). The increase in flux resulting from an increase in the fluid recirculation rate is caused by the decrease in the boundary layer thickness S. 

Figure 6.8 The effect of pressure on membrane flux for styrene-butadiene polymer latex solutions in a high-turbulence, thin-channel test cell [13]...

Figure 6.9 Ultrafiltration flux with a latex solution at an applied pressure of 60 psi (in the limiting flux region) as a function of feed solution latex concentration. These results were obtained in a high-turbulence, thin-channel cell. The solution recirculation rate is shown in the figure [13]...

Chibowski, S., Dependence of the adsorption behavior of polyvinyl alcohol at the polystyrene latex-solution interface on the molecular weight, J. Colloid Interf. Sci., 134. 174. 1990. 

Suspensions of polymer spheres of various diameter and surface functionality were templated to produce monoHthic silica containing dispersed spherical voids [33]. The pH of the aqueous latex solution was decreased to 2 before the... 

PEGylated-latex solution mixed with usual water soluble polymer has been shown by Tabuchi et al." to be an effective micro-CE (p--CE) medium for DNA separation. 

A latex solution provides a large solid-liquid interfacial area for modification. 

There are two general types of water-based adhesives solutions and latexes.Solutions are made from materials that are soluble only in water or in alkaline water. Examples of materials that are soluble only in water include animal glue, starch, dextrin, blood albumen, methyl cellulose, and polyvinyl alcohol. Examples of materials that are soluble in alkaline water include casein, rosin, shellac, copolymers of vinyl acetate or acrylates containing carboxyl groups, and carboxymethyl cellulose. 

The addition of the latex into the PC solution should provide a better means of covering the latex completely with polycation without coagulation. Therefore, we added to 10 mL PC solution of concentration Cc = 2 lO" g cm a latex solution of Cl = 9.35 10 g cm with a dosage rate Vp =... 

The polymerisation and the properties of the latexes depended sensitively on the emulsifier and on the charge of the initiator. There was no visible correlation between the properties of the final latexes and the properties of the emulsifiers such as surface activity, solubilisation capacity, or the ability to stabilise the initial monomer emulsion. When a cationic (2,2 -dimethyl-2,2 -azo-N-benzylpropionamidine hydrochloride, VA-552 from Wako Chemicals) initiator was employed, all emulsifiers lead to stable monodisperse latexes, except for polysoaps with low hydrophobe content. The polymerisable, as well as the polymeric emulsifiers, yielded latex solutions with very high surface tensions, different from the use of the standard surfactant. In contrast, the use of an anionic initiator (potassium persulphate) can pose difficulties. The... 

Commercially available PEDOT PSS (Clevios CPP105D, solid content 1.2% from H.C. Starck GmbH) and latex (Appretan 96100), at a ratio of 7 1, were combined by stirring at room temperature for 30 min. The PEDOT PSS/latex solution was then heated with stirring at 110°C. The solvent was removed at controlled levels until solutions comprising 15, 20, 25 and 30 wt% PEDOT PSS were obtained. The act of solvent removal increases the viscosity and the conductivity of the solutions. 

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