Study on Dielectric Monitoring on Polymerization Process of MMA

Polymethyl methacrylate (PMMA) is widely used in the fabrication of polymer optical fiber and devices. It is necessary to obtain lower loss PMMA by monitoring and controlling the polymerization process of methyl methacrylate (MMA). In this paper, a polymerization process monitoring system with two-electrodes is designed to investigate changes of dielectric properties of samples with reactive time during polymerization process of pure MMA. The relation of dielectric properties of samples and the conversion rate of MMA is obtained based on a two-phase model of composite. Simultaneously, the influence of reactive temperature, reactive time, conversion rate of prepolymerization and oxygen on polymerization process is discussed. It is shown that the gel effect will be observed in 2h after beginning of reaction at 50°C, when conversion rate of prepolymer is 24% without oxygen. This new method showed high efficiency compared with the refractive index measurement for the monitoring of polymerization process.