Binder decomposition

The effects of oxides on the binder burnout of poly(vinyl butyral) (PVB) was studied by Masia et al. [26]. The binder decomposition kinetics in air was shown to be a strong function of the ceramic oxide present. In all cases, the oxide decreased the temperature necessary for thermal decomposition compared to PVB alone. The order was the following ... 

Calvert et. al. describes a theoretical model to calculate the bum out time as a function of the extrudate thickness without bubble formation [Cal 90]. By increasing early development of porosity within the sample, higher debinding temperatures can be used and consequently faster burnout can be achieved. Furthermore the products of the binder decomposition should have a high vapor pressure and should diffuse rapidly through the extruded body. 

Binder burnout continues to be an active area of ceramics research with one of the main thrusts being in developing models of binder decomposition and diffusion. 

In addition to characterizing binder decomposition, thermal analysis is also useful to characterize precursor powder decomposition and dehydration prior to sintering. 

Binder K 1983 Collective diffusion, nucleation, and spinodal decomposition in polymer mixtures J. Chem. Phys. 79 6387... 

The Beckstead-Derr-Price model (Fig. 1) considers both the gas-phase and condensed-phase reactions. It assumes heat release from the condensed phase, an oxidizer flame, a primary diffusion flame between the fuel and oxidizer decomposition products, and a final diffusion flame between the fuel decomposition products and the products of the oxidizer flame. Examination of the physical phenomena reveals an irregular surface on top of the unheated bulk of the propellant that consists of the binder undergoing pyrolysis, decomposing oxidizer particles, and an agglomeration of metallic particles. The oxidizer and fuel decomposition products mix and react exothermically in the three-dimensional zone above the surface for a distance that depends on the propellant composition, its microstmcture, and the ambient pressure and gas velocity. If aluminum is present, additional heat is subsequently produced at a comparatively large distance from the surface. Only small aluminum particles ignite and bum close enough to the surface to influence the propellant bum rate. The temperature of the surface is ca 500 to 1000°C compared to ca 300°C for double-base propellants. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

Lipson (1943, 1944), who had examined a copper-nickeMron ternary alloy. A few years ago, on an occasion in honour of Mats Hillert, Cahn (1991) mapped out in masterly fashion the history of the spinodal concept and its establishment as a widespread alternative mechanism to classical nucleation in phase transformations, specially of the solid-solid variety. An excellent, up-to-date account of the present status of the theory of spinodal decomposition and its relation to experiment and to other branches of physics is by Binder (1991). The Hillert/Cahn/Hilliard theory has also proved particularly useful to modern polymer physicists concerned with structure control in polymer blends, since that theory was first applied to these materials in 1979 (see outline by Kyu 1993). 

K. Binder. Spinodal decomposition. In P. Haasen, ed.. Materials Science and Technology, Vol. 5. Weinheim VCH-Verlag, 1990. 

Horton (H9, H10) has obtained additional acoustic-admittance data for a series of composite propellants. At a given frequency, decreasing the mean oxidizer particle size increases the acoustic admittance and thereby the tendency for instability. Horton also investigated the effects on the acoustic admittance of the incorporation of traces of copper chromite, a known catalyst, for the decomposition of ammonium perchlorate, lithium fluoride (a burning-rate depressant), and changes in binder these data are difficult to analyze because of experimental errors. 

The decompositions of these compounds are of interest since they are used as binders in electron-emissive coatings [1023]. The initial stage of the endothermic reaction in vacuum or nitrogen (520—820 K) yields residual carbonate and a small quantity of carbon. Changes in surface area during reactions have been measured. The main volatile product is HCHO, but secondary, exothermic reactions occur on the surface of the product carbonate so that the overall reaction is... 

Few studies have been conducted to determine organic residues in spent foundry sand and leachates from disposal sites. It is reported that several organic compounds are present in the spent foundry sand but have concentrations below the regulated toxicity characteristic limits. Organic compounds of concern include benzoic acid, naphthalene, methylnaphthalenes, phenol, methylenebisphenol, diethylphenol, and 3-methylbutanoic acids.12 These compounds are thought to be derived from the decomposition of organic binders such as phenolic urethane, furan, and alkyd isocyanate. 

Gums are complex carbohydrates exuded from plants, or produced by the decomposition of vegetable matter, that have been used since remote times as adhesives, sizes, and binders (see Table 73). Most gums are tasteless and odorless solids that either dissolve or swell in water to form adhesive, viscous mucilages. When the water evaporates from a mucilage, the... 

P.R.81 is used especially in three and four color printing and lends itself to various printing processes, therefore pigments of this type are referred to as Process Red in the USA. Used as a colorant for NC-based printing inks, SM types of P.R.81 may present problems as they are dispersed with steel balls or stored in steel containers as well as at elevated temperature. Catalytic decomposition of the binder and damage to the pigment may induce a color shift and increase the viscosity. 

Thermal degradation studies might be required to determine the decomposition characteristics of of the subject pesticide vAien heated alone or In the presence of oxidizers and/or binders In both closed and open systems and at various temperatures. 

Following Cahn s theory, more extended versions were proposed by Langer et al. [ O] and Binder et al. [ l] Recently, de Gennes [52], and Pincus [53] applied spinodal decomposition to polymer mixtures. Many of the recent experimental studies on spinodal decomposition of polymer mixtures deal with measuring characteristic scattering maxima with various scattering techniques [5A-60]. 

Binder and Frisch [ ] constructed free energy functions for spinodal decomposition in IPN s. They predict initial domain wavelengths which are both larger and smaller than the typical distances between network crosslinks. In the latter case, they anticipate a coarsening of the structure until the domain size becomes comparable to the distances between crosslinks. This, indeed, is what An, et al. [ I ] found, because a wavelength of... 

The type of spinodal decomposition encountered in IPN formation differs from the classical temperature quench in the sense that a composition change constitutes the driving force, at a fixed temperature. In this case, the rate of composition change is deeply involved in the phase separation process [6 ], which severely limits the applicability of current spinodal theory. In fact. Binder and Frisch [ ] which assume the polymerization rate is rapid enough to limit the phase separation. On the contrary, in the experimental work by Lipatov et al. [ ], the rate of polymerization was kept to a minimum to make the conversion changes during the phase separation minimal. 

The burning rate of propellants is one of the important parameters for rocket mo-tordesign. As described in Section 7.1.2, the burning rate of AP composite propellants is altered by changing the particle size of the AP used. The diffusional mixing process between the gaseous decomposition products of the AP particles and of the polymeric binder used as a fuel component determines the heat flux feedback from the gas phase to the condensed phase at the burning surface. - This process is a... 

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