Aqueous thermoplastic emulsions

Aqueous thermoplastic emulsions Fast air-dry/flow-temperature forced dry Film formation guidelines must be followed... 

Aqueous thermoplastic emulsions n. Water based acrylic emulsions with noncros-slinked latex particles. 

Aqueous Thermoplastic Emulsions n Water-based acrylic emulsions with noncrosslinked latex particles. 

Hiraishi et Resilon (PCL-based thermoplastic) Biodegradation by cholesterol esterase using agar-weU diffusion assay of serially diluted aqueous Resilon emulsions dispersed in agar... 

Adhesive Emulsions. Thermoplastic, synthetic polymers can be prepared as emulsions for use as adhesives. For example, while EVAc hot-melt adhesives described in the previous section contain less than 40% VAc, when the content of VAc in the copolymer is increased to 60%, and the copolymer is prepared in the form of aqueous emulsions, a very useful and versatile adhesive polymer is obtained. Although the VAc homopolymer, poly(vinyl acetate), is a brittle solid, with a Tg = 28 °C, the ethylene units present in the EVAc copolymer act as an internal plasticizer, and lower the Tg to below room temperature. The plasticization results from the reduction of interchain interaction of the VAc polymer chains by the ethylene units interspersed among the strongly interacting VAc units. This reduction of the Tg has important consequences because the formation of a flexible adhesive film from the emulsion depends upon the Tg of the polymer. 

Emulsion polymers (latexes) are the most commonly used film formers in the coating industry this is particularly the case with aqueous emulsion paints that are used for home decoration. These aqueous emulsion paints are applied at room temperature, when the latexes coalesce on the substrate to form a thermoplastic film. Occasionally, functional polymers are used for crossUnkirig in the coating system. The polymer particles are typically in the submicron range (0.1-0.5 pm). 

Polystyrene is a transparent, colorless thermoplastic resin available in solvent-solution or aqueous-emulsion form. In both forms, appUcations are limited to conditions where at least one of the adherends is porous. An example is sticking polystyrene tiles onto a plaster wall. Polystyrene adheres well to wood, but not to plastics, except itself. For bonding polystyrene, a low-molecular-weight styrene polymer with a peroxide catalyst is used. This adhesive polymerizes in the glue Une. ° ... 

The resinous thickeners above are thermoplastic and all ultimately soluble in one solvent blend or another. As we have seen, their low shear effects can be destroyed by solvent additions. If, however, the polymers are made as latexes or non-aqueous dispersions by emulsion or dispersion polymerization (Chapter 11) and a small amount of cross-linking is introduced via polyfunc-tional monomer, then insoluble colloidal resin particles are produced. These are called microgels. 

The preparation of polyurethane lattices is possible in several ways. In one instance special monomers are polymerized in an aqueous medium to produce a thermoplastic polyurethane emulsion. Or thermoplastic polyurethanes made in solution or dissolved in solvents are emulsified in water, then solvent is removed. Or an isocyanate-terminated urethane prepolymer, possibly with hydrophilic branches, is blocked with an appropriate isocyanate blocking agent, and emulsified in water together with a crosslinking agent. 

Acrylics Solutions and aqueous emulsions Both thermoplastic and thermoset formulations available Very wide adhesion range Excellent resistance to discolouration, hght, and oxidation Curing types are available that have wash and dry-cleaning resistance Pressure-sensitive adhesives Laminating adhesives... 

Apart from the fluoro monomers vinyl fluoride (VF), vinylidene fluoride (VF2), and tetrafluoroethylene (TFE), only chlorofluoroethylene has found commercial use as homopolymer. It is applied as thermoplastic resin based on its vapor-barrier properties, superior thermal stability (Tdec > 350 °C), and resistance to strong oxidizing agents [601]. Chlorofluoroethylene is homo- and copolymerized by free-radical-initiated polymerization in bulk [602], suspension, or aqueous emulsion using organic and water-soluble initiators [603,604] or ionizing radiation [605], and in solution [606]. For bulk polymerization, trichloroacetyl peroxide [607] and other fluorochloro peroxides [608,609] have been used as initiators. Redox initiator systems are described for the aqueous suspension polymerization [603,604]. The emulsion polymerization needs fluorocarbon and chlorofluorocarbon emulsifiers [610]. 

Poly(vinylidene fluoride), PVDF or PVF2, is usually manufactured from radical initiated batch polymerization process in aqueous emulsion or suspension of CH2=CF2 monomer. PVDF is a thermoplastic that exhibits interesting properties, such as piezoelectric, pyroelectrical, and ferroelectric behaviors. PVDF has even superior dielectric permittivity arising from the strong polymerization originating from C—F bonds, and the spontaneous orientation of dipoles in the crystalline phases makes it a polar polymer with good compatibility with polar chemicals. 

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