On the particle kinetics in the synthesis of polymer grains via multiscale simulation of suspension polymerization

Understanding of the intricate interplay between particle kinetics and spatially heterogeneous distribution is crucial for synthesis of polymer grains. In this contribution, a comprehensive multiscale model based on computational fluid dynamics‐population balance model, including breakage and coalescence terms, is developed and validated with experimental data using vinyl chloride (VC) suspension polymerization as a case study. The colloid protection ability of dispersant‐polyvinyl alcohol (PVA) at the VC/water interface is quantified by introducing a modified factor η = 0.001875 for the coalescence term, accounting for surface coverage ratio ( Γ / Γ m ). Subsequently, for the non‐reactive stage, according to the simulated droplet size distribution (DSD) under different stirring speeds ( N ) and VC phase volume fractions ( φ ), a linear formula is developed to correlate d 32 of VC droplets with N −1.2 and φ , that is, d 32 = 66,034(1 + 2.236 φ ) N −1.2 + 12.96. For the reactive stage, relatively a higher stirring speed ( N = 600 rpm) enables a gradually increased d 32 during polymerization, taking variation of droplets/particles properties into account, which thus prevents the formation of larger PVC grains. This work offers insights into the multiscale phenomena during VC suspension polymerization and can be generalized to the production processes of other polymer grains.