Phenomenological modeling of vinyl-acrylic copolymer emulsion polymerization: Insights from pilot and industrial plants

At an industrial scale, the manufacturing of Vinyl Acetate (VA) and Butyl Acrylate (BA) copolymer emulsions faces significant challenges due to complex reaction kinetics, high heat release, and the need for effective temperature control. Another difficulty emerges when analyzing dynamic behavior across pilot and industrial scales, as scale differences often lead to discrepancies in product properties and control challenges. To address these issues, this work develops and validates a phenomenological-based semi-physical model (PBSM) capable of representing the dynamics of emulsion polymerization consistently across both scales. The model integrates free-radical polymerization kinetics, particle formation, mass and energy balances, and recirculation through a shell-and-tube heat exchanger. Validation using experimental data from 0.3-ton pilot and 13-ton industrial reactors demonstrated strong predictive accuracy with temperature errors below 1.1% (MAPE) and polymer concentration errors of 10.34% (pilot) and 7.60% (industrial) during the 4-hour continuous dosing period under 338-345 K control range. Sensitivity analysis with ±20% parameter variations revealed inverse relationships between VA/BA monomer feed concentration ratio and both polymer conversion and viscosity, while lower agitation causes localized temperature increases and reduced mixing efficiency. The model's capability to identify and quantify scale-dependent effects provides a robust computational tool for process optimization, control strategy development, and reliable scale-up from pilot to industrial emulsion polymerization processes.