Solidification Rheology

Injection molding processing involves both a molten flow phase and a solidification phase. The major challenges of constitutive modeling of the liquid-solid transition involve two related topics. First, one needs to eonsider how the flow and thermal history influence the structure of the fluid. Seeondly, one needs to understand how the ehanges in the internal strueture stiffen the material. There are some investigations on the topics for semicrystaUine materials and a variety of approaches or models have been proposed by different authors. Most of these results are reviewed by Tanner and Qi (2005) and Pantani et al. (2005). However, 

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This system of equations is solved numerically. The results obtained are physically reasonable up to the axial position where crystallization commences, where the rate of cooling slows down because of the exothermic solidification phenomenon and the rheological properties change sharply. 

Computer techniques have been and are still being further developed to simulate this complex mould-filling process, so that, for a given geometry and given rheological parameters and solidification behaviour, it can be predicted. This procedure results in a considerable improvement of the product quality, since it enables optimisation of the mould design. 

Although heat treatment leads to improved properties, no further drawing steps are required to generate highly oriented systems. Hence, the orientation which is found in fiber and injection molded specimens must arise during flow and be maintained during the solidification process. The final physical properties must therefore be directly related to the rheological properties of the liquid crystalline fluids. 

Clustering of RBC is a very important and vital biological process (e.g., see [131]), which influences the rheological properties of blood and may lead to severe cardiovascular problems, such as anemia, ischemia, angina, thrombosis, and stroke. Clotting process is accomplished by the solidification of blood. It initiates three separate, but overlapping, hemostatic mechanisms ... 

The injection molding process includes both molten polymer and solidification phase, where flow and crystallization may take place simultaneously. Therefore, for modeling injection molding, a rheological relation connecting the relative crystallinity a to flow parameters is needed. 

On the other hand, the processing of liquid-crystalline polymers has received considerable interests. One of the most unique aspects of liquid crystalline fluids is the rigid-rod constituents capability to orient during processing. Furthermore, these orientations and the resultant texture could be maintained during the solidification process. Hence, the rheological properties of spinning dopes are directly correlated to the final mechanical properties of fibers. 

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