Meaning
Molecular diffusion rates describe how quickly a slip additive moves from the center of a molded part to the outer surface. The secondary amide migration kinetics determine the time it takes for a film to reach its target friction value after it leaves the extruder. Unlike primary amides, secondary amides move slowly and provide a more stable surface over time.
Diffusion Rate
Concentration gradients drive the movement of the additive through the polymer matrix. Because of the specific secondary amide migration kinetics, these molecules take days or even weeks to reach an equilibrium state. This delay must be accounted for when testing the quality of a new batch of film.
Surface Accumulation
Density of the lubricant on the surface increases as more molecules arrive from the bulk. The secondary amide migration kinetics ensure that once the molecules reach the surface, they are less likely to bloom or create a dusty appearance. This leads to a cleaner finish on high-end packaging.
Storage Duration
Performance of the material changes based on how long it has been since it was produced. Understanding the secondary amide migration kinetics allows a manufacturer to predict when a roll of film will be ready for the printing or laminating stage.
