Akademik Veri Yönetim Sistemi
PHASE TRANSITIONS, cilt.79, sa.11, ss.863-873, 2006 (SCI-Expanded)
The steady-state fluorescence (SSF) technique was used to study the sol-gel transition for the linear bulk polymerization of butyl methacrylate (BMA), carried out above the glass transition temperature of polybutylmethacrylate (PBMA) (T-g = 20 degrees C). Pyrene (P-y) was used as the fluorescence probe. The increase in P-y intensity was monitored during free radical polymerization of BMA by using SSF technique. Changes in the viscosity of the pregel solutions due to gel formation dramatically enhance the fluorescent yield of aromatic molecules. This effect is used to monitor the sol-gel transition of BMA, as a function of time, at various temperatures. The results are interpreted in the view of percolation theory. The gel fraction exponent beta = 0.39 +/- 0.02 agreed the best with the static percolation values for the linear bulk BMA polymerization carried out above T-g but weight average degree of polymerization exponent, gamma deviated from the percolation results.