Polymer latex definition

There are many unique polymerization processes which share a conunon heritage with emulsion polymerization, but which often are unrecognized as such. It is the purpose of this review to describe some of these emulsion polymerization-like processes and their products. Some further definition is in order unconventional emulsion polymerizations can be described as those processes whereby the product is a polymer latex that physically resembles latex from emulsion polymerization and cannot be grouped into any other recognized form of heterogeneous polymerization. In many cases the reasons why a process is not recognized as an emulsion polymerization is that the polymerization is not via a free-radical process. This review (hscusses four distinct types of polymerization processes, all of which have examples that produce latex particles and in many ways can be described as unconventional emulsion polymerizations. These are free-radical polymerization, ionic polymerization, transition metal catalyzed polymerization and enzyme-catalyzed polymerization. The precise systems discussed in this review are described in Table 23.1. 

For instance, in order to increase the polymer concentration of polymer latexes, multimodal and/or broad PSDs may be required [47]. It must also be stressed that the PSD and the polymerization rates are coupled in many heterogeneous polymerizations. This leads to the definition of the fifth classical control problem, which is the control of some features of the PSD of the final polymer material. 

The rubber may be natural, in which case the latex is produced by the rubber tree. Latex of the main synthetic rubbers is produced by the technique of emulsion polymerisation. The term latex has been broadened in recent years and a general definition is now a stable dispersion of a polymeric substance in an aqueous medium . Latices may be classified as natural (from trees and plants), synthetic (by emulsion polymerisation) and artificial (by dispersion of the solid polymer in an aqueous medium). They may also be classified according to the chemical nature of the polymer, e.g., SBR, nitrile, polychloroprene, etc. 

Silicone co-polymer networks and IPNs have recently been reviewed.321 The development of IPNs is briefly described, and the definitions of the main (non-exclusive) classes of the IPNs are cited. Examples of latex IPNs, simultaneous and sequential IPNs, semi-IPNs, and thermoplastic IPNs are provided. The use of silicone-silicone IPNs in studies of model silicone networks is also illustrated. Networks in which siloxane and non-siloxane components are connected via chemical bonds are considered co-polymer networks, although some other names have been applied to such networks. Today, some of the examples in this category should, perhaps, be discussed as organic-inorganic hybrids, or nanocomposites. Silicone IPNs are discussed in almost all of the major references dealing with IPNs.322-324 Silicone IPNs are also briefly discussed in some other, previously cited, reviews.291,306... 

Spectroscopy. Infrared and UV spectra were run on the 5 latex samples described in Table I to provide information for interpretation of subsequent application test results, and as a guide for GPC detector settings. In both cases, the absorption of the ferrocene moiety is largely obscured by the absorption of the parent polymer, thus limiting these techniques for definite analy-... 

Consider a monodispersed latex, where water-phase termination is negligible and termination is instantaneous when a radical enters a polymer particle containing one radical. By definition, IV2 = IV3 = — = 0 and the total radical entry rate per liter of latex equals p. Application of the stationary-state hypothesis gives... 

Pre-crosslinked Latex Blends. In these materials the individual latexes are crosslinked during synthesis, then blended, and a film is formed. Because of limited deformation and/or interdiffusion capabilities, such films tend to be weak, and only used for special purposes [Zosel and Lay, 1993 Lesko and Sperry, 1997], However, light crosslinking, as occurs in SBR latexes, may be tolerated. Pre-crosslinked latex blends materials are actually not IPNs, because the definition requires that at least one of the polymers be polymerized and/or crosslinked in the immediate presence of the other. An application of pre-crosslinked suspension-polymerized blends, in anionic and cationic form, is as ion-exchange resins. In suspensions, the particles are larger, usually of the order of 10-200 pm. 

Relation Between Surface Hardness and Compressive Straigth. The surface hardness of latex-modified systems is generally improved to some extent over ordinary cement systems, depending on the polymer type and the polymer-cement ratio. A definite correlation between the surface hardness and compressive strength of most latex-modified systems is recognized as shown in Fig. 4.29.1 ... 

CAS 9002-88-4 EINECS/ELINCS 200-815-3 Synonyms Ethene, homopolymer Ethene polymer Ethylene homopolymer Ethylene latex Ethylene polymer Ethylene polymers Ethylene resin PE Polyethylene resins Polyethylene wax Polythene Definition Thermoplastic resin obtain by polymerizing ethylene Empirical (CjH,),... 

Classification Vinyl ester monomer Definition Vinyl ester of neononanoic acid Ermnula CH2=CHOCOCR, where R is methyl or greater Uses Reactive intermediate for polymerization for copolyrner latexes, water-sol. polymers, thermosetting coatings, adhesives, inks, textile sizing... 

Definition Polyoxyethylene, polyoxypropylene block polymer of ethylene diamine Properties Nonionic Toxicoiogy TSCA listed Uses Emulsifier, thickener, wetting agent, dispersant, solubilizer, stabilizer in cosmetics, pharmaceuticals demulsifier in petrol, industry detergent ingred. antistat for polyethylene and resin molding powds. polymerization in latex-based paints, aq.-based syn. cutting fluids and vulcanization of rubber... 

Classification Polymer synthetic elastomer Definition Unsaturated polymer of chloroprene Empirical (C4HsCI)x Formula [CH2CH=CCICH2]x Properties As solid, latex, or flexible foam m.w. 100,000-300,000 dens. 1.23-1.35 brittle pt. -35 C softens. 80 C ref. index 1.5512 (20 C) high tens, str. resilient resistant to oils, oxygen, ozone, elec, current, abrasion... 

See Vinyl acrylic copolymer Vinyl acetate resin. See Polyvinyl acetate Vinyl acetate/vinyl chloride copolymer Vinyl acetate/vinyl chloride polymer. See Vinyl chloride/vinyl acetate copolymer Vinyl acetate/vinyl neodecanoate copolymer Definition Latex emulsion contg. 50-55% solids polymer comprised of 65-85% VA and 15-35% vinyl neodecanoate Uses Binder in emulsion paints... 

Latexes made out of composite polymer particles (i.e., particles containing different phases) present definitive advantages in many applications. Thus, particles formed by an elastic core and a hard shell are used as impact modifiers for polymer matrices [14]. Hard-core, soft-shell particles are particularly useful for paints because they have a low MEET and are not sticky at higher temperatures [16]. Hollow particles are efficient opacifiers [15], and... 

The actual stained latex. Figure 6.9, appears to lie between Figures 6.11a and 6.11b. Most particles are slightly but definitely darker near the exterior than in the center, consistent with a higher concentration of polymer II, P(B-cc -AN), toward the exterior. An early stage of latex coalescence is apparent from the attachment points between particles, but these are light in the micrograph because they are only 70 to 150 A thick. 

The above represents the classical definition of an IPN. The term interpenetrating polymer network was coined before the extent or conseqnences of phase separation were fully realized. This article covers sequential and simultaneous types of IPNs made in bulk and also includes such materials as IPNs based on latexes and suspension-sized particles thermoplastic IPNs, which contain physical cross-links in one or both polymers, and hence may be (partly) soluble and a number of other closely related materials. 

Latex IPNs, by definition, have their origin in emulsion polymerization. Several types of latex IPNs exist. If one blends two kinds of latex particles, followed by film formation and cross-linking of both polymers, the material is called an interpenetrating elastomeric network, TEN. Usually, lENs form a three-dimensional mosaic structure (69,70). 

Non-ionic surfactants by definition carry no charge and with these surfactants stabilisation is mainly by volume reaction. Again the hydrophobic portion is adsorbed on the polymer surface while the hydrophilic portion, usually long ethylene oxide chains, extends into the water phase. Because of the volume occupied by these ethylene oxide chains the polymer particles cannot easily approach each other, i.e. there is an energy barrier to coalescence due to the spatial presence of the adsorbed surfactant. Stabilisation by this means is termed steric stabilisation . The energy barrier to coalescence can be reduced by reducing the proportion of the ethylene oxide chains, e.g. either by salt addition or by heating the latex. 

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