화학공학소재연구정보센터
Polymer Engineering and Science, Vol.33, No.24, 1644-1652, 1993
Effects of Kinetic and Transport Parameters on Accelerated Migration of Reactive Additive from Plastic Sheet
The effects of kinetic parameters Hatta number Ha and phi, and transport parameters Biot number Bi and psi on the migration of a reactive additive have been modeled. The convective boundary layer can be considered inert to fully reactive for Ha --> 0 to 2, respectively. The migration is controlled by diffusion. reaction rate, equilibrium partitioning of the migrant between the plastic film and the solvent, and boundary layer resistance, depending on the time scale and values of the above parameters. For a nonreactive boundary layer, at high Bi, migration is initially diffusion-controlled but becomes reaction-rate controlled at later times. However, under similar conditions, a slight increase in the reactivity of the boundary layer immediately changes the transport process from diffusion-controlled to reaction rate-controlled. With fur-ther increase in reactivity, migration spontaneously reaches equilibrium, At low Bi, equilibrium partitioning and reactive depletion of the migrant in the fluid phase change predominantly to boundary layer-controlling mass transport phenomenon. For a given sampling time (tau = 1.0), the migration increases with the increase in Bi only for a reactive boundary layer. At low Bi and (tau = 1.0), migration decreases only up to phi is-approximately-equal-to 0.3 for nonreactive to partially reactive boundary layer, but for inter-mediate and high Bi, phi and Ha do not influence migration.