Welding polymer pair

In contrast, high-power or low-frequency ultrasound can be used to compatibi-lize immiscible polymer pairs by the high shear and degradation of the polymer chains. Moreover, in many cases there was no deterioration in mechanical properties, despite a lowering of both the molecular weight and viscosity. Dramatic improvements in the weld line strength of immiscible PS/HDPE blends were... 

Diffusion in polymer-polymer systems is important in many practical applications, such as crack healing, polymer blending, welding, adhesion, elastomer tack, polymer fusion, and many others. However, diffusion coefficient data is lacking due to the complexity of the polymer diffusion process. Typical techniques employed are infrared spectroscopy, spectroscopic ellipsometry, and optical schlieren. Only a few studies of interdiffusion in polymer pairs are reported. Depending on the temperature and other physical parameters of the system, Fickian and Case II diffusions (see Section 4.3) can be observed with varying relative importance (Jabbari and Peppas, 1993). 

Polymer flow issues are concerns on the part of plant operations personnel that can arise when one proposes to put an in-line NIR probe (or pair of probes) into a polymer reactor or transfer line. These concerns tend to be plant or process-specific. Plant personnel are likely to be concerned if the probe will change the pressure drop in the line, create a cold spot in the reactor or line, protrude into the flow stream, or create dead spots (e.g. recessed probes or the downstream side of protruding probes). There may also be plant- or process-specific resfricfions on where probes (or analyzers) can be located, on pipe sizes, on the use of welds, and on materials of construction. It is critical to involve plant operations personnel (including process operators) as early as possible in discussions about probe design and location. 

We begin this chapter by discussing the factors that determine whether or not a given pair of polymers will form a molecular mixture at equilibrium. Then we will discuss the structure at equilibrium of the interface between two immiscible polymers, introducing as we go two powerful theoretical approaches that we will use later in the book for a variety of more complex surface and interface problems. Finally, we will discuss the ways in which interfaces arise and attain their equilibrium structure firstly considering processes such as welding in which we take two pure polymers and attempt to... 

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