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Thermal and nuclear magnetic relaxation studies of water–sodium polystyrene sulfonate systems
Author(s) -
Hatakeyama T.,
Hatakeyama H.
Publication year - 1990
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.1990.220010504
Subject(s) - materials science , differential scanning calorimetry , atmospheric temperature range , relaxation (psychology) , polystyrene , phase (matter) , analytical chemistry (journal) , thermodynamics , phase transition , glass transition , sulfonate , activation energy , sodium , nuclear magnetic resonance , chemistry , organic chemistry , polymer , composite material , psychology , social psychology , physics , metallurgy
The phase transition behavior of water–sodium polystyrene sulfonate (NaPSS) systems was investigated by differential scanning calorimetry (DSC), 1 H and 23 Na nuclear magnetic resonance spectroscopy (NMR) in a temperature range from 150 to 330 K, and in a water content (W c = grams of water/gram of dry sample) range from 0 to 2.5. With slow cooling from the isotropic liquid state, the system formed the liquid crystalline state and the crystalline state. The temperature range of the liquid crystalline state became broader with deceasing W c . When the system contained an excess amount of free water, the liquid crystalline state was not observed. The 1 H longitudinal relaxation time (T 1 ) of the system showed a minimum value in the temperature range where the liquid crystalline state was observed. At the same time, the 1 H transverse relaxation time (T 2 ) dropped at the transition temperature from the isotropic liquid to the liquid crystalline state (T * ). The correlation time (τ c ) was calculated using modified Woessner's equations. The variation of τ c as a function of temperature agreed well with the phase diagram obtained from DSC. The 23 Na T 1 and T 2 values were correlated with W c and temperature. The activation energy was calculated to be from 20 to 25 KJ/mol depending on W c . The formation of the liquid crystalline phase of NaPSS is affected by 10–20 water molecules, which can be categorized as freezing bound water.