Acrylic latex behavior

The second objective is to verify experimentally the predicted relationship between polymer polarity and surfactant adsorption by studying the adsorption of a non ionic surfactant that shows a saturation type isotherm behavior on vinyl acrylic latexes of varying polarity. 

Figure 5 shows the swelling behavior of the model acrylic latexes as determined by photon correlation spectroscopy. Changes in particle diameter are shown instead of radius as in Figures 3 and 4. The diameter, d, at each pH was divided by the initial diameter, d0, determined at pH = 5 (unexpanded). In general shape, the curves are similar to those determined by sedimentation and viscometry. The initial points occurred at a higher pH due to the much lower particle concentration. No effort was made to lower the initial pH with acid consequently, the undesirable salt effect was avoided. 

The lower curve in Figure 6 shows the sedimentation behavior of a PMMA latex containing 2% acrylic acid added in Stage II in the same manner employed to make the model carboxylic acrylic latex. A contraction of approximately 75 A was observed at pH = 11. 

Table I compares typical test results for low-, mid-, and high-effective molecular weight thickeners in a vinyl-acrylic latex paint. Many of the same trends are present with cellulosic and HE UR thickeners when the effective molecular weight designation for HEUR thickeners is used. As the effective molecular weight of an HEUR increases, Stormer thickening efficiency, roller spatter, and water resistance increase, whereas ICI viscosity decreases. The major difference between these two thickener types is in their low-shear behavior. As effective molecular weight increases, cellulosic paints improve in leveling and decrease in sag resistance. HEUR paints decrease in leveling and improve in sag resistance. Other property differences between these two thickener types are highlighted in Table II.

Figure 11. Characteristic expansion behavior for a soft acrylic latex containing 1% acrylic acid, as measured by sedimentation technique, showing effect of electrolyte on particle expansion. (Bassett and Hoy, Ref. 32)...

Ferguson et al. [52] compared the behavior of a range of conventional alkyl ethoxylate surfactants in emulsion polymerizations with their acrylated analogues. This has allowed a direct comparison of identical surfactant structures, one of which remains kinetically mobile in the resultant lattices, while the other becomes chemically bound to the latex particles. The surfactants chosen for this study were C12 i4-(EO)30 with C12 14-(EO)30-A and C12 14-(EO)12 with C12 14-... 

Recent investigations have shown that the behavior and interactions of surfactants in a polyvinyl acetate latex are quite different and complex compared to that in a polystyrene latex (1, 2). Surfactant adsorption at the fairly polar vinyl acetate latex surface is generally weak (3,4) and at times shows a complex adsorption isotherm (2). Earlier work (5,6) has also shown that anionic surfactants adsorb on polyvinyl acetate, then slowly penetrate into the particle leading to the formation of a poly-electroyte type solubilized polymer-surfactant complex. Such a solubilization process is generally accompanied by an increase in viscosity. The first objective of this work is to better under-stand the effects of type and structure of surfactants on the solubilization phenomena in vinyl acetate and vinyl acetate-butyl acrylate copolymer latexes. 

R. A. Dickie, M. F. Cheung, and S. Newman, Heterogeneous Polymer-Polymer Composites. II. Preparation and Properties of Model Systems, J. Appl. Polym. Sci. 17, 65 (1973). Latex Semi-IPNs. Poly(methyl methacrylate)/poly(n-butyl acrylate). Synthesis, morphology, mechanical behavior. 

L. H. Sperling, T.-W. Chiu, R. G. Gramlich, and D. A. Thomas, Synthesis and Behavior of Prototype Silent Paint, J. Paint Technol. 46,47 (1974). Constrained layer damping. Latex IPNs. Methacrylic/acrylic compositions. 

The present communication is confined to a report on the behavior of a copolymer of acrylonitrile and acrylic acid regulated with n-octyl mercaptan. The alkali salt of this copolymer is water soluble and shows considerable stabilizing power in latex, but it is without the foaming tendencies which are produced in latex by conventional emulsifiers. 

The agglomerating methods described above are economical, reliable, and effective and have been used in the production of impact-resistant resins. But the mechanism and the characteristics of these agglomerating processes have not been reported in the literature therefore, in this chapter, the behavior and the mechanism of agglomeration was studied using poly(n-butyl acrylate) as the agglomerated latex A, and n-butylacrylate-acrylic acid copolymer as the agglomerating latex B, based on the interaction between hydrophilic free polymer and polymer latex. 

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