Interior profiles

Interior profile formulation for single and twin extruders. [Data from Rapacki, S. R., J. Vinyl Additive TechnoL, 4,1,12-21,1998.]... 

Methacrylate-butadiene-styrene (MBS). Methacrylate-butadiene-styrene represents the highest volume of the styrenic type impact modifiers. This modifier is used in transparent packaging applications due to its clarity. Rigid applications include film, sheet, bottles, credit cards, and interior profiles. MBS has hmited use in exterior applications due to poor ultraviolet (UV) stability. Methacrylate/acrylonitrile-butadi-ene-styrene (MABS) is closely related to MBS, but has minor use in the industry and has been completely replaced by MBS in North America. 

In Europe, one wood-plastie extrusion company (Fasalex GmbH) based in Austria has produced wood-reinforeed biodegradable polymer products for various interior applications (e.g., interior profiles, mouldings). The Fasalex line ineludes products based on natural fibres in combination with maize starch and various percentages of non-degradable polymers, sueh as PP or PVC, as well as one material that is almost entirely made firom renewable resources. Fasalex products for exterior use are said to be under development. 

A low Reynolds number indicates laminar flow and a paraboHc velocity profile of the type shown in Figure la. In this case, the velocity of flow in the center of the conduit is much greater than that near the wall. If the operating Reynolds number is increased, a transition point is reached (somewhere over Re = 2000) where the flow becomes turbulent and the velocity profile more evenly distributed over the interior of the conduit as shown in Figure lb. This tendency to a uniform fluid velocity profile continues as the pipe Reynolds number is increased further into the turbulent region. 

R. H. Singleton, Potash Mineral Commodity, Profiles MCPll, U.S. Department of the Interior, Bureau of Mines, Washington, D.C., Feb. 1978, pp. 12-13. 

Schematic DRD shown in Fig. 13-59 are particularly useful in determining the imphcations of possibly unknown ternary saddle azeotropes by postulating position 7 at interior positions in the temperature profile. It should also be noted that some combinations of binary azeotropes require the existence of a ternaiy saddle azeotrope. As an example, consider the system acetone (56.4°C), chloroform (61.2°C), and methanol (64.7°C). Methanol forms minimum-boiling azeotropes with both acetone (54.6°C) and chloroform (53.5°C), and acetone-chloroform forms a maximum-boiling azeotrope (64.5°C). Experimentally there are no data for maximum or minimum-boiling ternaiy azeotropes. The temperature profile for this system is 461325, which from Table 13-16 is consistent with DRD 040 and DRD 042. However, Table 13-16 also indicates that the pure component and binary azeotrope data are consistent with three temperature profiles involving a ternaiy saddle azeotrope, namely 4671325, 4617325, and 4613725. All three of these temperature profiles correspond to DRD 107. Experimental residue cui ve trajectories for the acetone-...

When a carrier is impregnated with a solution, where the catalyst deposits will depend on the rate of diffusion and the rate of adsorption on the carrier. Many studies have been made of Pt deposition from chloroplatinic acid (HgPtClg) with a variety of acids and salts as coim-pregnants. HCl results in uniform deposition of Pt. Citric or oxalic acid drive the Pt to the interior. HF coimpregnant produces an egg white profile. Photographs show such varied distributions in a single pellet. 

When measuring AU profiles, the voltage drop is measured along the interior of the casing [2]. The voltage drop is caused by cell currents as in Section 18.2.1 or by cathodic protection currents. The anodic and cathodic sections of the casing and also the effect of the cathodic protection can be determined from the AU profiles. 

Fig. 10 shows the radial particle densities, electrolyte solutions in nonpolar pores. Fig. 11 the corresponding data for electrolyte solutions in functionalized pores with immobile point charges on the cylinder surface. All ion density profiles in the nonpolar pores show a clear preference for the interior of the pore. The ions avoid the pore surface, a consequence of the tendency to form complete hydration shells. The ionic distribution is analogous to the one of electrolytes near planar nonpolar surfaces or near the liquid/gas interface (vide supra). 

Part cures were characterized by exothermic reaction wave propagation. Figures 6a-9b show the development of the reaction waves. The waves propagate from the walls of the part towards the center. A comparison of the temperature and epoxide conversion profiles revealed that the highest temperature corresponded to the highest conversion. As the part initially heats the resin/glass matrix nearest the walls heats fastest however, as the part exotherms the temperatures in the interior of the part exceeded the wall temperatures. The center temperature does not become the hottest temperature until the waves intersect. It must be noted that the hottest temperature does not always occur at the center of the part. The wave velocities are proportional to the wall temperatures. In Figures 6a to 9b the mold temperature was 90 C and the press temperature was elevated to 115 C. Since the press does not heat the part until after it is wound, the press temperature was elevated to accelerate the reaction wave from the press so that the waves would intersect in the center of the part. 

We use variants of profile extrusion to produce tubing -with diameters of less then 1 mm and pipes with diameters exceeding 1 m, Wall thicknesses can vary from a few tens of micrometers up to several centimeters. Extruded window and door frames are more complex than pipes. Such profiles are largely hollow with internal ribs and fins that reinforce and divide the interior into two or more channels. We use solid rubber profiles in applications such as door seals and windshield wipers. We can produce foamed extrudates by incorporating a blowing agent, such as butane or carbon dioxide, into the polymer in the molten state. As the polymer exits the die, its internal pressure drops and the dissolved gas expands to form bubbles within the product. Examples of foamed extrudates include pipe insulation and automobile door gaskets. 

A kinetics or reaction model must take into account the various individual processes involved in the overall process. We picture the reaction itself taking place on solid B surface somewhere within the particle, but to arrive at the surface, reactant A must make its way from the bulk-gas phase to the interior of the particle. This suggests the possibility of gas-phase resistances similar to those in a catalyst particle (Figure 8.9) external mass-transfer resistance in the vicinity of the exterior surface of the particle, and interior diffusion resistance through pores of both product formed and unreacted reactant. The situation is illustrated in Figure 9.1 for an isothermal spherical particle of radius A at a particular instant of time, in terms of the general case and two extreme cases. These extreme cases form the bases for relatively simple models, with corresponding concentration profiles for A and B. 

In Figure 9.1(c), the opposite extreme case of a very porous solid B is shown. In this case, there is no internal diffusional resistance, all parts of the interior of B are equally accessible to A, and reaction occurs uniformly (but not instantaneously) throughout the particle. The concentration profiles are flat with respect to radial position, but cB decreases with respect to time, as indicated by the arrow. This model may be called a uniform-reaction model (URM). Its use is equivalent to that of a homogeneous model, in which the rate is a function of the intrinsic reactivity of B (Section 9.3), and we do not pursue it fiirther here. 

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