Comparision of critical parameters of polymerization and gelation processes: A fast transient fluorescence study
Yükleniyor...
Tarih
2005-03-10
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
World Scientific Publ Co Pte Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The fast transient fluorescence technique was used to study free-radical polymerization and crosslinking copolymerization of styrene. Ethylene glycol dimethacrylate and Pyrene were used as crosslinking agent and fluorescence probe, respectively. The fluorescence lifetimes of Pyrene from its decay traces were measured and used to monitor the vitrification processes at various temperatures. Changes in the viscosity due to polymer formation dramatically enhanced the fluorescent yield of pyrene molecules. This effect is used to monitor the polymerization and crosslinking copolymerization of Styrene as a function of time, at various temperatures. The results are interpreted in the view of static percolation theory. The critical exponents ß and ? for vitrified fraction and average degree of polymerization were found to be 0.39 ± 0.012; 1.62 ± 0.036 and 0.39 ± 0.004; 1.69 ± 0.064 in agreement with percolation results for polymerization and gelation processes, respectively. Activation energies for polymerization and gelation (?EP and ?EG) were measured and found to be 112.0 ± 4 and 86.9 ± 4 kJ mol-1, respectively.
Açıklama
Anahtar Kelimeler
Activation energies, Critical exponents, Fast transient fluorescence technique, Percolation theory, Polymerization and gelation, Cross-linking copolymerization, Molecular-size distribution, Free-radical polymerization, Sol-gel transition, Glass-transition, Methyl-methacrylate, Critical exponents, High conversions, Rate constants, Polymers
Kaynak
International Journal of Modern Physics B
WoS Q Değeri
Q2
Scopus Q Değeri
Q2
Cilt
19
Sayı
6
Künye
Kaya Aktaş, D. & Pekcan, M. Ö. (2005). Comparision of critical parameters of polymerization and gelation processes: A fast transient fluorescence study. International Journal of Modern Physics B, 19(6), 971-987. doi:10.1142/S0217979205029390
