Length scale of mixing

Spin-diffusion NMR techniques, typically involving abundant homonuclei like H and F, are an important and powerful avenue for interrogating heterogeneous systems. Excellent reviews of this area have recently been published [55,56]. While the general use of spin-diffusimi to probe length scales of mixing in polymer blends, or to... 

Characterization of HME-based solid dispersions is not solely motivated by the need to directly measure physical failure. By extension, characterization tools and techniques provide insight into the fundamental properties which facilitate physical failure. For instance, measures of the thermodynamic properties and modes of motion associated with amorphous systems serve to better assess risk of physicochemical failure. Also, as was noted above, in several instances, although the material may be rendered amorphous, the differences in length scale of mixing may manifest as differences in performance, and, thus, characterization tools also inform process development. 

Miscible Blend Dynamics and Length Scales of Mixing... 

Chapter 3 provides a brief review of recent developments in areas of amorphous polymer blends. Differential mixing, chain dynamics, and glass transition properties for individual polymer components in miscible binary blends, as well as new methods to experimentally acquire such information, are considered. Miscible blend dynamics and length scales of mixing of amorphous polymer blends are discussed. Amorphous biopolymer blends involving polymers obtained from renewable feedstocks is also briefly reviewed. 

Prandtl mixing length, length scale of turbulence... 

As seen in Chapter 2 for turbulent flow, the length-scale information needed to describe a homogeneous scalar field is contained in the scalar energy spectrum E k, t), which we will look at in some detail in Section 3.2. However, in order to gain valuable intuition into the essential physics of scalar mixing, we will look first at the relevant length scales of a turbulent scalar field, and we develop a simple phenomenological model valid for fully developed, statistically stationary turbulent flow. Readers interested in the detailed structure of the scalar fields in turbulent flow should have a look at the remarkable experimental data reported in Dahm et al. (1991), Buch and Dahm (1996) and Buch and Dahm (1998). 

Most molecular mixing models concentrate on step (1). However, for chemical-reactor applications, step (2) can be very important since the integral length scales of the scalar and velocity fields are often unequal (L / Lu) due to the feed-stream configuration. In the FP model (discussed below), step (1) is handled by the shape matrix H, while step (2) requires an appropriate model for e. 

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