Monitoring Polymerization Kinetics of MMA using Ultrasonic Velocity Measurement

Jubair Ahamad, Benazeer , Mohd Ansari, Mohan Kalhans and Ajay Singh

Background and Objective: Ultrasonic studies are a powerful technique for probing molecular interactions and kinetic properties of monomeric mixtures. This study explores the use of ultrasonic velocity measurements to monitor the free-radical polymerization of methyl methacrylate (MMA) in methanol. Materials and Methods: Polymerization was initiated using 2,2 -azobisisobutyronitrile (AIBN) at 65±0.5°C. The reaction mixture contained 70 mL MMA, 30 mL methanol, and 0.2 g AIBN. Ultrasonic velocity measurements were recorded at 15-minute intervals over 2-3 hrs. Results: Ultrasonic velocity data revealed three distinct phases: an initial slight increase, a sharp rise during active polymerization, and a final plateau indicating saturation. Continuous velocity increase corresponded to progressive polymer formation and increased medium rigidity. Calculated adiabatic compressibility, acoustic impedance, and percentage conversion values further described the polymerization phase behavior. Conclusion: Ultrasonic velocity measurements provide a sensitive, non-destructive method to monitor polymerization kinetics, clearly distinguishing induction, active polymerization, and saturation stages in solution systems.

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