Blending processes, affecting factors

If the blending process is between two or more fluids with relatively low viscosity such that the blending is not affected by fluid shear rates, then the difference in blend time and circulation between small and large tanks is the only factor involved. However, if the blending involves wide disparities in the density of viscosity and surface tension between the various phases, then a certain level of shear rate may be required before blending can proceed to the required degree of uniformity. 

It must be emphasised that the various stages of phase separation and the final structures obtained depend on many factors, some of which are considered in later sections. The previous paragraphs represent idealisations of what may happen during real polymer blend processing. One of the most important factors that determine the behaviour of a polymer blend is the way that temperature affects the AG i curve, which is now considered. 

Credibility the credibility of the survey team will affect acceptance of the process and its outcomes. A blend of human factors (or applied psychology), safely and operational experience in the team seems to work best. The credibility of the internal coordinator is also important. A good safety champion within an ANSP is priceless. A key predictor in their effectiveness in this role relates to the quality of their cormections with both management and the operational workforce. 

In manufacturing and processing polymer blends, it is important that the viscosity ratio be within the optimal range in the actual processing conditions. Thus, not only the polymers to be blended but also the temperature and shearing conditions should be carefully selected. Other factors, such as interfacial tension and elasticity of the blended polymers, affect the blend morphology as well. 

Barrier polymers, 3 375-405 applications, 3 405 barrier structures, 3 394-399 carbon dioxide transport, 3 403 flavor and aroma transport, 3 403-405 health and safety factors, 3 405 immiscible blends, 3 396-398 large molecule permeation, 3 388-390 layered structures, 3 394-396 miscible blends, 3 398-399 oxygen transport, 3 402 permanent gas permeation, 3 380-383 permeability prediction, 3 399-401 permeation process, 3 376-380 physical factors affecting permeability, 3 390-393... 

The properties of block copolymers that are most affected by molecular architecture are elastomeric behavior, melt processability, and toughness in the solid state. The effects of such copolymers in polymer blends can obviously also be strongly influenced by the same factors. 

Overall, factors that might affect the adsorption of actives on the carrier surface include surface properties, moisture content, the type and particle size/shape of carriers and actives, as well as the mixing ratio of actives and carriers. Pharmaceutical processes (i.e., milling and granulation) could affect the adsorption process by altering carrier and active properties (i.e., surface properties, size, and shape), hence the characteristics of blending and the quality of the final dosage form. 

Two series of blends based on PEEK are available from Sumitomo, PEEK/LCP (Sumiploy EK) and PEEK/PES (Sumiploy SK). The blends are to be processed by injection molding. The critical factors affecting performance of both series of blends are crystallinity of the matrix resin (PEEK) and blend morphology. It is important to control the diameter-to-length ratio of LCP fibers or the particle size of PES dispersed in PEEK matrix to achieve the expected performance. 

Finally, shear viscosity is strongly affected by the clay in the blends, especially at high PEN contents. A lubricating effect rather than a filler effect reveals the possibility that the clay is not well dispersed in the polymer blend, and migration of particles in the flow to the wall region can explain the observed reduction in shear viscosity. When MMT clay is mixed with crystallizable polymers such as polyesters, some processing problems arise because the crystallization process is modifled by nucleation effects induced by the nanoparticles. Moreover, these particles also influence the kinetics of transesteriflcation between PET and PEN, besides other factors such as the reaction time and extruder processing temperature. In Reference 72, a quaternary alkyl ammonium compound (Cl8) and MAH were used to modify the surface properties of the clay... 

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