Flourescence method to study gelation swelling and drying processes in gels formed by solution free radical compolymerization
Gelation during solution free radical crosslinking copolymerization (FCC) of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDM) was studied by using the steady state fluorescence technqiue. FCC was performed in the presence of toluence at 75°C. Sol-gel transitions were monitored by observing the direct intensity of an excited pyrene (Py) during in situ fluorescence experiments for various toluence content. Gel points were determined and critical β exponents were found to be around 0.38. In situ swelling and drying experiments were performed at 50°C by monitoring Py intensity in disk-shaped gels produced by solution FCC. Li-Tanaka equation was employed to produce the cooperative diffusion coefficient, D c for swelling process. D c values were found to the around 10−6 cm2/s at 50°C. It was also observed that loosly formed gels swell much faster than densely formed gels.
Key wordsFluorescence percolation gelation swelling drying
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