Dieletric Relaxation and Calorimetric Measurements of Glass Transition in the Glass-Forming Dyhydroxyl Alcohols

概要

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In order to sttrdy tlue unolectrlar weight dependence of tlae a-relaxation and glass transitions of"intermediate glass-forming rnaterials, the dielectric and therznal properties have been investigatedin both liquid and svnpercooled liquid states. By nuearts of' rnodtrlated DSC at 10 mHz andbroadband dielectric spectroscopy in the freqtrency range from 10 IIIHZ to lOGHz, propyleneglycol (PG) and its five oligomers (poly pr'opylene glycol, PPG), which have the sitnilar chetaaicalstructtrre btrt different uaaolecular weights 76 -4OOOg/naol, were sttrdied paying attention to theirfragility and cooperativity. Tlte f'ragility of' PG and PPGs froraa the dielectric and thermalmeasureraaents was analyzed and coraapstred using both the interrnolectrlar cooperativity xnodeland the Adana-Gibbs model, The Vogel-Ftrlcher energy and rninimtrun configurational entropywere evaluated for PG and PPGs using the counparison rnethod. Their values were related tothe density of -OH end group and its interrnolecular hydrogen bonding. The strength paratmeterdecreased with increasing molecular weight indicating that PG 111011011161' liqtrid is stronger thanPPG liquids. The domain size at T., whiclm was introdtrced by the Matsuoka's cooperativitymodel, was about 2 to 5 for PG and PPGs, increasing with molecular weight. The increase ofthe domain size in the vicinity of T. was shown to be related to the larger non-exponentiality,
社団法人日本物理学会の論文
1998-12-15