Alkyd constant

Solvents are selected such that some will escape relatively quickly from paint films to prevent excessive flow, while others will escape slowly to provide film leveling and adhesion. With typical alkyd coatings, the first 30% of solvent has been observed to evaporate as quickly as the neat solvents, essentially at a constant rate which is dependent on volatility. Later stage evaporation occurred several times more slowly and was rate-controlled by solvent diffusion to the surface of the paint film. The transition point between this behavior was defined as the resin solids content at which the evaporation rate due to volatility equaled that due to diffusion. Transition points have been observed to typically occur at a resin solids content of 40-50% v/v. Thus alkyd paints, normally formulated at 27-40% v/v resin solids, generally exhibit rapid initial solvent-release driven by volatility while high solids coatings (usually 65-75% v/v resin solids) dry solely by a diffusion-controlled process with negligible influence by solvent volatility (Ellis, 1983). 

A model for calculating viscosities of concentrated polymer solutions has been formulated and used successfully to predict viscosities of alkyd resin solutions in both pure aromatic solvents and in mixtures of hydrocarbons and oxygenated materials. It was also found to describe viscosity trends in polystyrene-diethylbenzene solutions accurately. The formulation explicitly accounts for the observation that concentrated solution viscosities increase markedly with decreasing compatibility between resin and diluent. The proposal of an empirical relationship which interprets the viscosity enhancement in poorer solvents in terms of increased chain-chain interactions is of interest. The model contains three constants which are fixed for a particular resin and are independent of diluent type. These are the Mark-HouuAnk constant, the parameter in the Martin viscosity equation, and the constant relating the postulated clustering to the solution thermodynamics of a particular solution. 

Glass-filled alkyd/polyester 14.8 6 resistant, low dielectric constant ... 

Flory has examined the kinetics of polyesterifications and found that the reactivity of the functional groups is essentially the same as the reactivity of functional groups in monofunctional esterifications. The velocity constant is independent of the molecular size up to a molecular weight of at least 10,000. Since there are molecules with a functionality greater than 2 present in alkyds, they are subject to gelation. The transformation from a viscous material to a gel is sudden. The formation of a small fraction of an infinite-network poljuner is the cause of this gelation. As the reaction continues, more of the gel phase is formed and the resin becomes more tough and less extensible. 

Nickel, tris( 1,10-phenanthroline)-racemization, 24,466 solid state, 467 structure, 64 Nickel(I) complexes magnetic properties, 274 Nickel(II) complexes, 470 allogonism, 207 equilibrium constants solvent effect, 516 isomerism, 184 liquid-liquid extraction, 544 magnetic properties, 274 5-mcrcaptoamine alkydation, 417 photoreactivity, 407... 

Allylic monomers are sometimes used with alkyds to produce polyesters, with the orthophthalate resin being the most widely used because of its lower cost and very low water vapor pressures. Alkyd-diallylphthalate copolymers have significantly lower exotherm than an alkyd-styrene copolymer. The electrical properties of allylic resins are excellent and the variations of dissipation factor, dielectric constant, and dielectric strength with temperature and frequency are given in Figs. 2.12 and 2.13. The surface and volume resistivities remain... 

Table 5.5 shows that some polymers have a particularly high dielectric constant that is, these polymers have greater ability to store power in a given volume of polymer. These are polyesters, alkyd resins, phenol-formaldehyde, nylon 6,6, nylon 6,10, urea formaldehyde, and plastized polyvinyl chloride (PVC), all of which have dielectric constant values of >5 at 1 kHz. Tsuchiya and coworkers [14] discussed... 

Optical properties and spectral reflection curves of P.Y. 185 and P.Y. 139 in an alkyd / melamine system at a constant pigment / Ti02 ratio of 1 10 are shown in Figure 14-13 ... 

Moisture (water or water vapor) can come from several sources, including water vapor in the surrounding air, rain, and condensation as temperatures drop at night. Paint films constantly absorb and desorb water to maintain equilibrium with the amount of moisture in the environment. Water is practically always present in the coating. In a study of epoxy, chlorinated rubber, alkyd and linseed oil paints, Lindqvist [13] found that even in stagnant air at 25°C and 20% relative humidity (RH), the smallest equilibrium amount of water measured was 0.04 wt %. 

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