Modeling Of Infrared Drying Of Polymer Solutions

This thesis presents the development of dynamic models for drying a coating polymer layer placed on fixed and moving substrate in a dryer using infrared (IR) heat source. The IR drying model is a set of coupled nonlinear partial differential equations (PDEs) arising from simultaneous mass and heat balances and they describe variations of the solvent concentration and the polymer system temperature during the drying process. The model was numerically solved in MATLAB environment and then validated using data from literature. Using polyvinyl acetate (in toluene) as a coating material on a polyester substrate, the simulation revealed that the model agrees with data and describes adequately well the drying kinetics. The modeling approach was also extended to simulate the drying of a polymer solution in a container. Since solvent and polymer molecular sizes are quite different, the diffusion coefficient was better described with free volume theory.

Modeling Of Infrared Drying Of Polymer Solutions

This thesis presents the development of dynamic models for drying a coating polymer layer placed on fixed and moving substrate in a dryer using infrared (IR) heat source. The IR drying model is a set of coupled nonlinear partial differential equations (PDEs) arising from simultaneous mass and heat balances and they describe variations of the solvent concentration and the polymer system temperature during the drying process. The model was numerically solved in MATLAB environment and then validated using data from literature. Using polyvinyl acetate (in toluene) as a coating material on a polyester substrate, the simulation revealed that the model agrees with data and describes adequately well the drying kinetics. The modeling approach was also extended to simulate the drying of a polymer solution in a container. Since solvent and polymer molecular sizes are quite different, the diffusion coefficient was better described with free volume theory.

Debonding waves in gel thin films

We develop a mathematical model for the sliding of a gel sheet adhered to a moving substrate. The sliding takes place by the motion of detached region between the gel sheet and the substrates, i.e. the propagation of a Schallamach wave. Efficient numerical methods are developed to solve the problem. Numerical examples illustrate that the model can describe the Schallamach wave and are consistent with the existing experiments qualitatively.

Mixing Versus Stirring

Mixing is the operation by which a system evolves under stirring from one state of simplicity—the initial segregation of the constituents—to another state of simplicity—their complete uniformity. Between these extremes, patterns emerge, possibly interact, and die sooner or later. This review summarizes recent developments on the problem of mixing in its lamellar representation. This point of view visualizes a mixture as a set of stretched lamellae, or sheets, possibly interacting with each other. It relies on a near-exact formulation of the Fourier equation on a moving substrate and allows one to bridge the spatial structure and evolution of the concentration field with its statistical content in a direct way. Within this frame, one can precisely describe both the dynamics of the concentration levels in a mixture as a function of the intensity of the stirring motions at the scale of a single lamella and the interaction rule between adjacent lamellae, thus offering a detailed representation of the mixture content, its structure, and their evolution in time.