Ferrocene-Based <i>Kickers</i> for the Radical Polymerization of Vinyl Chloride Under Suspension Conditions:Improvement of the Process

Polyvinyl chloride (PVC) is primarily manufactured via radical suspension polymerization of vinyl chloride monomer (VCM). Previously, dual-component ferrocene (Fc)-based kickers have been shown to enhance this process by facilitating the controlled decomposition of organic peroxides into radicals during the initiation step. However, these systems often introduce issues such as suspension destabilization, crusting, and reduced PVC thermal stability. This study evaluates alternative Fc-based kicker systems to address these challenges. Among the tested combinations, Fc/sodium hydroxymethanesulfinate (SFS) kicker proved most effective, reducing polymerization time by 24% while maintaining suspension stability. Additionally, PVC produced with Fc/SFS exhibited better thermal stability compared to previous systems employing Fc/ascorbyl palmitate (PAA). Nevertheless, uncontrolled energy release at high conversion rates posed challenges for industrial scalability. To address these issues, phase transfer agents, such as cetyltrimethylammonium bromide (CTAB), were incorporated alongside Fc/SFS to improve reactant interactions. Injecting CTAB at 40% VCM conversion stabilized the suspension and accelerated polymerization without excessive energy release. This optimized system achieved significant time savings while preserving PVC quality, presenting a promising solution for industrial implementation.