Plasticizers binder effects

In both explosives and propellants the materials are relatively non-porous. The binders and plasticizers used effectively fill the pore spaces. Pyrotechnics are porous and the heat transfer related to the hot gas permeation into the reactant material mixture becomes important. In many pyrotechnics no binders or plasticizers are used. The explosives and propellants have burning (or detonation) rates that depend on density, temperature, and pressure. However, the burning rates of pyrotechnics are, in addition, affected by porosity, particle sizes, purity, homogeneity (degree of mixing), and stoichiometry (fuel or oxidizer ratio). 

Blends of GRT and recycled HDPE from used milk containers were studied and patented (Coran and Howard, 1999 Howard and Coran, 2000). Effects of GRT particle size and concentration on mechanical and rheological properties were determined. The blend systems were optimized by a soft rubber-plastic binder produced from a mixture of HDPE and EPDM, wherein EPDM is dynamically vulcanized during its mixing with the HDPE. It was concluded that the softening of the HDPE binder provides compositions of improved ultimate mechanical properties. 

Adhesives. Poly(vinyl alcohol) is used as a component in a wide variety of general-purpose adhesives to bond ceUulosic materials, such as paper and paperboard, wood textiles, some metal foils, and porous ceramic surfaces, to each other. It is also an effective binder for pigments and other finely divided powders. Both fully and partially hydrolyzed grades are used. Sensitivity to water increases with decreasing degree of hydrolysis and the addition of plasticizer. Poly(vinyl alcohol) in many appHcations is employed as an additive to other polymer systems to improve the cohesive strength, film flexibiUty, moisture resistance, and other properties. It is incorporated into a wide variety of adhesives through its use as a protective coUoid in emulsion p olymerization. 

Increase hardness to reduce wear Minimize hinder plasticity Minimize agglomerate voidage Increase hinder concentration or change hinder. Binder plasticity strongly influenced hy hinder type. See above effects which decrease agglomerate voidage. 

The key to the successful application of high performance, pourable nitrocellulose plastisols lies in a reasonably priced, high quality source of fine-particle, at least partially colloided, spheroidal nitrocellulose. Here we are speaking of particles much finer than the well-known ball powder, produced by the Olin Mathieson Chemical Co. for small arms for over 30 years (7). Actually, particles on the order of 5-50/x diameter appear to be required to assure a reasonable continuum of uniformly plasticized nitrocellulose binder in a propellant containing 45% or more of combined crystalline oxidizer and powdered metal fuel. Such a continuum of binder is necessary to assure acceptable mechanical properties and reproducible burning characteristics of the finished propellant. Preincorporation of a certain content of the water-insoluble solids within the nitrocellulose microspheres is an effective means of helping to assure this continuum of binder and alleviates the requirements for extremely small ball size. The use of a total of 45% or more of crystalline oxidizer and (generally) metal fuel is essential if the propellant is to be competitive with other modern propellants now in service. 

Fig. 8. Effect of molding pressure P on the stress in compression (crc) for a carbonized foamed plastic made from a compound binder (wood resin, furfuryl alcohol, maleic anhydride) and phenolic microspheres 381...

Dressing EDS plastics (Table 20) reduces their water absorptivities considerably u. However, dressing agents added to the binder (active additives) are less effective than dressing of the glass surfaces (Table 21)2). 

The data in Fig. 13 show that the glass transition temperatures of all materials is reduced by the absorption of water. This seems to be due to the plasticizing effect of the water on the binder. There is a marked difference between the elastic states of the dressed and undressed foams, the latter becoming much more plastic after immersion in water. Increased plasticity is due to the loss of adhesion between the binder and the filler, indicating that water absorption by syntactic foams is multistaged. 

For a two-level factorial design, only two excipients can be selected for each factor. However, for the filler-binder, a combination of brittle and plastic materials is preferred for optimum compaction properties. Therefore, different combinations such as lactose with MCC or mannitol with starch can count as a single factor. Experimental responses can be powder blend flowability, compactibility, blend uniformity, uniformity of dose unit, dissolution, disintegration, and stability under stressed storage conditions. The major advantage of using a DOE to screen prototype formulations is that it allows evaluation of all potential factors simultaneously, systematically, and efficiently. It helps the scientist understand the effect of each formulation factor on each response, as well as potential interaction between factors. It also helps the scientist identify the critical factors based on statistical analysis. DOE results can define a prototype formulation that will meet the predefined requirements for product performance stability and manufacturing. 

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