Akademik Veri Yönetim Sistemi
Phase Transitions, cilt.78, sa.12, ss.915-926, 2005 (SCI-Expanded, Scopus)
Sol-gel and gel-sol phase transitions of kappa-iota (κ-) carrageenan mixtures in two types of salts were studied using photon transmission technique. Here, KCl and CaCl 2 were chosen as the proper salts for the carrageenan mixtures. Coil-to-double helix (c-h) and double helix-to-dimer (h-d) phase transitions of carrageenan mixtures in monovalent and bivalent cation solutions were studied upon heating and cooling by using photon transmission technique. Photon transmission intensity, I tr was monitored against temperature to determine the (c-h) and (h-d) transition temperatures ( T ch and T nd ). Two distinct transition regions were observed in both heating and cooling of the carrageenan-bivalent CaCl 2 salt system. At the first step of heating process dimers decompose into double helices by making (d-h) transition. At the high temperature region (h-c) transition takes place. Carrageenan-monovalent KCl salt system presented only (c-h) and (h-c) transitions upon cooling and heating processes. Transition temperatures at the heating and cooling processes were obtained. A hysteresis was observed between (h-c)-(c-h) and (d-h)-(h-d) transitions for the monovalent and bivalent cations respectively.