Characterization of latex

Characterization of Latex Particles with Respect to Carboxyl Distribution. All latex samples were cleaned by the serum replacement technique (10). Diluted latex sample (3% by weight) was placed in the cell confined with a Nuclepore membrane and distilled deionized water was fed into the cell from a reservoir placed at 1.5 meters above the cell. The serum from the cell exit was collected and monitored with conductance measurement. 

T Palosuo. Purification and molecular characterization of latex allergens. In Latex Protein Allergy The Latest Position. Brickendonbury, United Kingdom Crain Communications Ltd, Rubber Consultants, 1995, pp. 11-15. 

El-Aasser, M.S. (1983) Methods of latex cleaning. In G.W. Poehlein, R.H. Ottewill and J.W. Goodwin (eds). Science Technology of Polymer Colloids. Surface Characterization of Latexes. Characterization, Stabilization and Application Properties, Vol. 11, No. 68. Martinus Nijhoff Publishers, The Hauge, p. 422. 

Figure J.2AACFandCCF characterization of latex particles (diameter 109 nm) at 21 C in suspension [98] (by permission of Steinkopff Verlag GmbH Co. KG).

Guo et al. [150] described the synthesis and characterization of latex particles consisting of a PS core and a shell of linear PAA chains. In the first step, PS cores were covered by a thin layer of a photoinitiator 2-[p-(2-hydroxy-2-methylpropiophenone)] ethylene glycol-methacrylate (HMEM) by means of a seeded emulsion polymerization process. The polymer formed by HMEM on the surface acted as a photoinitiator in the next step, in which acrylic acid was nsed as a water-soluble monomer. The PAA chains were affixed on the surface by means of an attaching from technique that led to particles with well-defined morphology and narrow size distribntion. 

Santos, R.M. and Forcada, J. 1996. Synthesis and characterization of latex particles with acetal functionality. Prog. Colloid Polym. Sci. 100 87-90. 

The Metravib Micromecanalyser is an inverted torsional pendulum, but unlike the torsional pendulums described eadier, it can be operated as a forced-vibration instmment. It is fully computerized and automatically determines G, and tan 5 as a function of temperature at low frequencies (10 1 Hz). Stress relaxation and creep measurements are also possible. The temperature range is —170 to 400°C. The Micromecanalyser probably has been used more for the characterization of glasses and metals than for polymers, but has proved useful for determining glassy-state relaxations and microstmctures of polymer blends (285) and latex films (286). 

Moller, M., Kayma, M., Vieluf, D., Paschke, A., and Steinhart, H. (1998). Determination and characterization of cross-reacting allergens in latex, avocado, banana, and kiwi fruit. Allergy 53,289-296. 

The parameters K1/ K2/ and K3 are defined by the refractive indices of the crystal and sample and by the incidence angle [32]. If the sample has uniaxial symmetry, only two polarized spectra are necessary to characterize the orientation. If the optical axis is along the plane of the sample, such as for stretched polymer films, only the two s-polarized spectra are needed to determine kz and kx. These are then used to calculate a dichroic ratio or a P2) value with Equation (25) (replacing absorbance with absorption index). In contrast, a uniaxial sample with its optical axis perpendicular to the crystal surface requires the acquisition of spectra with both p- and s-polarizations, but the Z- and X-axes are now equivalent. This approach was used, through dichroic ratio measurements, to monitor the orientation of polymer chains at various depths during the drying of latex [33]. This type of symmetry is often encountered in non-polymeric samples, for instance, in ultrathin films of lipids or self-assembled monolayers. 

The determination of adsorption isotherms at liquid-solid interfaces involves a mass balance on the amount of polymer added to the dispersion, which requires the separation of the liquid phase from the particle phase. Centrifugation is often used for this separation, under the assumption that the adsorption-desorption equilibrium does not change during this process. Serum replacement (6) allows the separation of the liquid phase without assumptions as to the configuration of the adsorbed polymer molecules. This method has been used to determine the adsorption isotherms of anionic and nonionic emulsifiers on various types of latex particles (7,8). This paper describes the adsorption of fully and partially hydrolyzed PVA on different-size PS latex particles. PS latex was chosen over polyvinyl acetate (PVAc) latex because of its well-characterized surface PVAc latexes will be studied later. 

Ali, S. A. Sengupta, M. J., Preparation and characterization of monodisperse polystyrene latexes of varying particle sizes without the use of surfactants, Polym. Mater. Sci. Eng. 1991, 8, 243 250... 

Bonardi, C., Christou, Ph., Llauro-Darricades, M.E., Guillot, J., Guyot, A. and Pichot, C., 1989, Polymer Latex III International Conference, Characterization of Acrylic Latexes Functionalized by N-Methylol Acrylamide, 6/1-6/14, Plastics and Rubber Institute, London. 

Parod, R. J. and Brain, J. D. (1983) Uptake of latex particles by macrophages characterization using flow cytometry. Am. J. Physiol. 245, Cell Physiol. 14), C227-C234. 

Marshall, T. R., C. S. Parmenter, and M. Seaver, 1976. Characterization of polymer latex aerosols by rapid measurement of 360° light scattering patterns from individual particles, J. Colloid Interface Sci., 55, 624-636. 

The foregoing methods developed for the preparation and characterization of monodisperse polystyrene latexes to be used as model colloids can also be applied to the characterization of industrial latexes. The recipes used for the preparation of these industrial latexes are complex, and most contain a small amount of a functional monomer, e.g., acrylic acid, 2-sulfoethyl methacrylate, or N-methylolacrylamide. These functional monomers are often predominantly water-soluble, so that their use may have several results (i) the monomer may polymerize in the aqueous phase to form a water-soluble polymer that remains in the serum ... 

In these density profiles the latex particles, added before starting the experiment, migrate to that position in the cell where their density coincides with the density of the surrounding medium. The position of the particles can be recorded by schlieren optics or, if there is a particle density distribution, more precisely by scanning extinction measurements normally used for the characterization of proteins. Thus the density and extinction profile in the ultracentrifugation cell yield a criterion for the density distribution and hence, because of the correlation between chemical composition and particle density, a criterion for the composition distribution or heterogeneity of the latex particles. 

Characterization of the Polystyrene Latex Samples. The polystyrene, PS, latex samples under investigation were characterized according to particle size, concentration of surface sulphates and electrophoretic mobility, em, in deionized water. The results, Table I, show that all the samples were of similar size with the exception that the Dow latexes were monodisperse while... 

For this description of PCS, it is evident that, for mono-disperse systems, the technique can provide an absolute measurement of hydrodynamic size knowledge of the density or refractive index of the particles is not required, and no calibration or correction is needed. With the advent of digital correlators and microprocessors, PCS has also become a very fast and precise technique. Recent studies of latex using PCS include adsorbed layers (8), particle sizes (16), surface characterization (17) and aggregation (181- ... 

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