Process Capability Indices for Engineering Plant Scale Up
Process capability indices degrade during engineering scale up as transport gradients and raw material dispersion expand process variance beyond pilot baselines.
Polymerization Dispersion
Meaning
Chemical processes create small plastic or rubber particles within a liquid medium where they are not soluble. In polymerization dispersion, the reaction occurs in a system that uses stabilizers to prevent the growing particles from clumping together. This method produces a stable latex or suspension of solid polymer in water or organic solvent.
It is a primary technique for making coatings and adhesives.
Particle Morphology
Control over the size and shape of the resulting beads is achieved by adjusting the stirring speed and the concentration of the surfactant. Smaller particles generally lead to smoother films and better penetration in porous materials. The distribution of these sizes affects the viscosity and the drying characteristics of the final product.
Solvent Medium
The choice of liquid determines the temperature range of the reaction and the safety requirements for the facility. Water based systems are preferred for their low environmental impact and ease of handling. Organic solvents are used when the polymer is sensitive to moisture or requires a specific evaporation rate.
Surface Tension
Chemical additives reduce the energy at the interface between the monomer and the liquid phase. This stabilization is vital for maintaining the integrity of the dispersion during the entire reaction time. Without proper tension management, the mixture would separate and the polymer would form a solid mass that could damage the reactor.
The reaction must be monitored constantly to ensure the particles remain suspended.