Radiation‐induced polymerization of glass forming systems. VI. Polymerization rate at higher conversion in binary systems

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Abstract
The effect of temperature and composition on the inflection point in the time–conversion curve and the saturated conversion was investigated in the radiation‐induced radical polymerization of binary systems consisting of a glass‐forming monomer and a solvent. In the polymerization of completely homogeneous systems such as glycidyl methacrylate (GMA)–triacetin and hydroxyethyl methacrylate (HEMA)–propylene glycol systems, the time–conversion curve has an inflection point at polymerization temperatures between Tvm (Tv of monomer system) and Tvp (Tv of polymer system). Such conversions at the inflection point changed monotonically between 0 and 100% in this temperature range. Tv was found to be 30–50°C higher than Tg (glass transition temperature) and a monotonic function of composition (monomer–polymer–solvent). The acceleration effect continued to 100% conversion above Tvp, and no acceleration effect was observed below Tvm. The saturated conversion in homogeneous systems changed monotonically between 0 and 100% for polymerization temperatures between Tgm (Tg of monomer system) and Tgp (Tg of polymer system). Tg was also a monotonic function of composition. No saturation in conversion was observed above Tgp, and no polymerization occurred below Tgm. In the polymerization of completely heterogeneous systems such as HEMA–dioctyl phthalate, no acceleration effect was observed at any temperature and composition. The saturated conversion was 100% above Tg of pure HEMA, and no polymerization occurred below this temperature in this system.