Blend Characteristics

To the extent that motor octane is dependent on aromatic and isoparaffin content, motor octane increases in an FCC unit will be difficult to achieve. Thermodynamics does not allow the production of highly branched isoparaffins in an FCC unit, and blending studies show that motor octane is relatively insensitive to the aromatic content of an FCC gasoline in the range of 35-507e aromatics. However, a more aromatic gasoline may have better blending characteristics in that less aromatics from other sources will be required to achieve the same motor octane number increase. 

The fundamental relationships between compatibilization and selective blending on the blend characteristics and the foaming behavior, as demonstrated in the following, will not only be valid for this particular blend system, but will help to understand and control the foaming behavior of multiphase polymer blends in general. 

The first group, resins that are used primarily to toughen epoxy adhesive systems, is described in Chap. 8. This chapter focuses on the resinous modifiers that are used as alloy blends. Characteristics of commercially available epoxy alloy adhesives are presented in Table 7.1. Tensile shear and peel strengths that are typical of these hybrid adhesives are compared in Table 7.2. 

Fuel density is important for blending characteristics, but also relates to emission levels, fuel consumption, and emission control systems. Similarly, the viscosity of the fuel is important. Kinematic Viscosity is included in the Biodiesel Standard because it relates directly to the injection system performance. In the Biodiesel Standards, viscosity is often set at a specific temperature point. With most fatty acid methyl esters this is never a problem, but viscosity changes at low temperature can be much more problematic. Biodiesel tends to thicken faster than fossil diesel. Specific additives might be required to deal with this. 

Milling can affect the adsorption of actives on the carrier surface by altering the surface properties of excipients. It was noticed that milled actives frequently failed blend uniformity criteria, but unmilled active batches consistently met the blend uniformity criteria. By adding lubricant magnesium stearate, the blending content uniformity of the milled batches can be significantly improved. A small amount of amorphous materials could affect the blending characteristics of a direct compression formulation. ... 

ETBE is a valuable component for gasoline, with properties similar to, and in some cases better than, MTBE (Table 11.1). ETBE has, in fact, the same blending characteristics as MTBE but it has the additional benefits of a lower solubility in water, a lower volatility (some additional light compounds can be introduced in the gasoline pool without affecting its RVP) and moreover it allows a higher plant production capacity (16% wt). 

Park, and S.-E. Cho Study of the relationship between Hoffmann s list smoke components and leaf compounds, biological test, physical properties, blending characteristics of Korean tobacco 59th Tobacco Science Research 1860d. 

A recent commercial blend of ABS contains thermoplastic polyurethane elastomer as the main blend component. The blend was introduced in 1990 by Dow Chemical Co., under the trade name Prevail . These blends characteristically exhibit low modulus (340 to 1000 MPa) and high impact strength at low temperamres, e.g. notched Izod values of 370 to 1500 J/m at -29°C. The TPU component of the blend imparts high toughness and also allows paintabihty without a primer. ABS component imparts heat resistance (for paint ovens) and good tensile strength in the blend. The blend is projected to find applications in the automotive markets, particularly as paintable, soft bumper fascias. Typical properties of commercial ABS/TPU blends are shown in Table 15.6. 

In all of the work published to date the major concern has been with the description and evaluation of the blending characteristics of static mixers. In early discussions of mixing rate the concept of the number of sub-divisions of flow produced per static mixer element was used as an illustration of mixing rate. This was frequently interpreted as the hypothetical number of striations (r j) in a mixture pattern produced from equal volumes of segregated black and white materials. A relationship was proposed for the Kenics mixer. 

Data are available for the blending characteristics of the Sulzer SMV mixer, see Figure 12.10. As with the laminar data for the SMX and SMXL types the data are presented as the relationship between variation coefficient ([Pg.244]

Calico ka-li- ko [Calicut, India] (1578) n. A plain, closely woven, inexpensive cloth, usually cotton or a cotton/manufactured fiber blend, characteristically having figured patterns on a white or contrasting background. Calico is typically used for aprons, dresses, and quilts. 

Dagli S.S., Xanthos M. and Biesenberger J. A. (1992), Blends of Nylon 6 and Polypropylene with Potential Applications in Recycling, Effects of Reactive Extrusion Variables on Blend Characteristics , American Chemical Society Symposium, Vol. 513. 241-257. 

Binary Interaction Parameters and Blend Characteristic Pressures for Certain Polymer Systems [18]... 

Figures 10.6(a) and (b) show the remaining portion of the blends after extraction from water and xylene at 100 °C and 140 °C, respectively. Comparative studies were carried out for both unvulcanized and vulcanized blends after water (12 h) and xylene (4 h and 8 h) extraction. Water was used for TPS extraction, whereas xylene was used as an extracting solvent for HDPE and uncrosslinked NR. This method was generally used to determine the gel content related to the crosslink density. The degree of crosslink density was responsible for the blend characteristics and had a major influence on the tensile properties. After extraction with water (12 h), more than 90% of the blends were still remaining. This showed that water was not effective in extracting the TPS phase completely, which probably was due to TPS particles being entrapped in the matrix phase.

Polybutadiene (BR rubber) and the random styrene/butadiene copolymer (SBR rubber) are the most widely used polymers. Their principal use is in tyres, which are typically blends of natural/synthetic rubber. BR rubber has good resilience, abrasion resistance and low heat build-up. SBR contains 10-25% styrene which is added chiefly to reduce cost but also to improve wearing and blending characteristics compared with BR alone. BR and SBR are polymerized by a free-radical mechanism as a water emulsion at 50-60 °C (hot rubber) or 0°C (cold rubber). Typical compositions are 70% trans-1,4, 15% cis-1,4 and 15% 1,2. Ziegler systems used in solution polymerization yield an SBR which has higher MW, narrower MWD and higher cis-1,4-content than the emulsion free-radical type. 

The interfacial behaviour between the component polymers in blends to a large extent controls the bulk polymer blend characteristics. The understanding of these interfaces is therefore of vital importance. The neutron reflection (NR) technique is ideally suited to study polymer interfaces since it provides a composition profile perpendicular to the interface with a resolution on a sub-nanometer length scale. From self consistent mean-field theory for immiscible homopolymers of infmite molecular weight the interfacial width (w) is is related to the Floiy Huggins interaction parameter ( f) by iv=( )f-j6x a is the segment length) [1]. Therefore, simply by... 

Stronger position in the market place than the bare plastic. Attention has been especially focused on blends since the commercialization of General Electric s Noryl, a blend of HIPS with poly(2,6-dimethyl-l,4-phenylene oxide). We are now in a period of investigating both the new blends and related compound systems and the scientific principles underlying blend characteristics [1,2]. 

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