PVAc latex films

We have found that in the system of presulfate initiator, the PVAc latexes are not dissolved transparently in the methanol-water mixture [8], and in the system of HPO initiator, the extraction of the polymer from the PVAc latex films with acetone greatly depends on the polymerization condition [9]. These results suggest that if a polymerization method can be found in which the grafting polymerization of VAc onto PVA is controlled to the minimum, a large portion of PVAc in the latex film will have a chance of extraction with solvents. In this Chapter, the preparations of the unique porous films from the PVAc latexes containing PVA as a protective colloid by an extraction of the PVAc particles with acetone and the characteristic properties of the porous films are summarized. 

Figure 2 Electron microphotographs of crack surface (a) and (b) and upper surface (c) and (d) of PVAc latex film. Acetone extraction (a) and (c) before, (b) and (d) after.

There has been a conventional sense that the PVAc latexes prepared in the presence of PVA as a protective colloid contain the graft copolymer of PVA and PVAc, so that PVAc particles in the dried latex film are not extracted at a high ratio with solvents. In this Chapter, it has been defined without an influence by the usual sense that the porous PVA-PVAc composite can be prepared from the PVAc latex film with acetone extraction. The porous film consists of the spherical cells of PVA... 

Figure 3.38. dC /dT versus temperature data for a PMMA/PVAc latex film annealed at 140°C... 

Wetting agents that can be used with polyvinyl acetate homo- and copolymer emulsions are listed in Table 15. The effect of various surfactants on PVAc latex film structure and properties has been studied. ... 

Porous membranes with selective permeabiUty to organic solvents have been prepared by the extraction of latex films prepared with moderate ratios of PVA—PVAc graft copolymer fractions. The extracted films are made up of a composite of spherical cells of PVA, PVAc microgel, and PVA—PVAc graft copolymers (113). 

The PVAc latex was cast 1.8 mm in thickness on a poly(-ethylene) plate and dried at room temperature. The latex film was dried further in a vacuum desiccator for 24 h, and extracted in Soxhlet extractor with acetone for 20... 

Judging from the extraction percentage of PVAc and from the swelling degree of latex films in acetone, it is... 

From the electron micrographs, assuming that PVAc particles in the latex are the same size, the formation model of the porous film from the latex film can be illustrated as in Fig. 3 [19]. When the latex forms a dried film over minimum film-forming temperature, it is concluded that PVA coexisted in the latex and is not excluded to the outside of the film during filming, but is kept in spaces produced by the close-packed structure of PVAc particles. 

Figure 3 Formation model of porous PVA film from PVAc latex.

Figure 2.102. Use of the derivative reversing heat capacity to study interfacial effects this figure shows the application of this method to poly(methylmethacrylate)-poly(vmyl acetate) (PMMA-PVAc), (50 50) latex film [from Song et al. (1999) reprinted with permission from Springer-Verlag],...

This prediction is drawn according to the following model. Figure 5 illustrates that in the latex state the grafting PVA protects hydrophobic PVAc particles in water by concentrating on the surfaces of PVAc particles, but in the porous film after acetone extraction, the insoluble grafting PVAc conversely exists as an important component on the inner surface of spherical cells of PVA. 

Uses Surfactant, emulsifier, pigment wetting agent/dispersant, color acceptance agent for industrial coating systems, esp. latex paints, and for solvent-borne architectural paints, printing inks, adhesives, latexes food pkg. adhesives defoamer in food-contact paper coatings Features Low-foam remedies defoamer-induced film defects suitable for PVAc, acrylics, S/B, PVC/PVdC, alkyds, HC resins, NC, PU, epoxy, polyesters... 

Hazardous Decomp. Prods. CO, CO2, acrid fumes NFPA Health 2, Flammability 3, Reactivity 2 Uses Monomer for synthesis of nitrile rubber, PVAc emulsions, PVOH, EVA copolymers, vinyl chloride-vinyl acetate copolymers, PVBI, and vinyl acetate-acrylonitrile copolymers in polymerized form for plastic masses, films, lacquers, latex paints, adhesives, textile finishing, safety glass interlayers textile hand modifier binder for paper coatings esterification for food starch modified film-former in cosmetics food pkg. adhesives resinous/polymeric food-contact coatings for polyolefin films food-contact paper/paperboard, ionomeric resins, copolymers, laminates, resin-bonded filters, textiles... 

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