Microscale modeling techniques

This section is an overview of the most important deterministic and stochastic modeling techniques to obtain the polymer microstracture as a function of monomer conversion and polymerization conditions at the microscale. It is assumed that, for this scale, the bulk concentrations and temperature are known. The simplest case is the simulation of a batch polymerization reactor on laboratory scale with perfect macromixing and isothermicity implying a reactor with spatial homogeneity of the bulk concentrations and temperature. 

The most powerful property of the detailed microbalance models, especially in combination with visualization techniques, is the a priori prediction of (observable) macroscale phenomena. This can be particularly helpful in reducing the required experimental effort. Important problems are the amount of detailed information required for the microscale transport equations and the large progranuning and computational efforts required to solve specific problems. Nevertheless, these types of models, by generating insight in the micro- and... 

In this work, microscale evaporation heat transfer and capillary phenomena for ultra thin liquid film area are presented. The interface shapes of curved liquid film in rectangular minichannel and in vicinity of liquid-vapor-solid contact line are determined by a numerical solution of simplified models as derived from Navier-Stokes equations. The local heat transfer is analyzed in term of conduction through liquid layer. The data of numerical calculation of local heat transfer in rectangular channel and for rivulet evaporation are presented. The experimental techniques are described which were used to measure the local heat transfer coefficients in rectangular minichannel and thermal contact angle for rivulet evaporation. A satisfactory agreement between the theory and experiments is obtained. 

Emulsion polymerization is a powerful technique for developing products for a wide range of industry. The process can be used for the development of structured products in the nano- to microscales. Some of the key advantages of the process are the use of mild conditions, the near-complete conversion of monomers, the minimization of separation and recycling, the improved heat and mass transfer, and the improved environmental benefits due to the use of a water medium. However, the process is complex and requires careful modeling and scale-up. The prediction of process behavior, the key product properties, and the control of emulsion polymerization systems in particu-... 

In multiscale modeling approaches the microscopic behavior of a system is linked by a compression operator to the macroscopic state variable. The strategy is then to use the microscopic model to provide necessary information for extracting the macroscale behavior of the system. Such a combined macro-microscale technique is supposed to be much more efficient than solving the full microscopic... 

---