Thermal and dielectric studies of 2,2’-dihydroxybenzophenone

Effects of the presence/absence of hydroxyl or amine groups in mono/di-substituted benzenes on the α and β structural relaxation properties in liquids and glasses

“…This indicates that the activation energy of the b process is influenced by the liquid structure and determined by the intermolecular force. We have furthermore showed that the crystal nucleation which requires the reorientation of the whole molecules is caused much below T ga , indicating the presence of a floppy region within the glasses [7,16,[29][30][31]. The present results, summarized in Table 1, and the discussion described above give some hints to further advancement of such understanding on the structure and molecular rearrangements.…”

“…The b process may be interpreted to be the rearrangement of the molecules that are located in between the ordered regions and packed rather in the random way. Such a picture of statically heterogeneous liquid/glass structure has been postulated so far [7,16,[29][30][31] by us to explain diverse phenomena found in glassy and deeply supercooled liquid states, and the presence of such a structure with preordered domains has been really observed recently in the surface structure of silica and silicate glasses [32].…”

“…The fact that the tan d b,max of the compounds with hydroxyl group is smaller than that with amine group supports this interpretation: the fraction of the molecules located in the gap is expected to be smaller for the compounds forming stronger hydrogen bonds. The experimental result that IPP with hydroxyl group within the substituent undergoes the crystallization rather easily above the glass transition region would be related to this situation, since the crystal nuclei are recognized as a kind of structurally ordered region [16,[29][30][31].…”

“…With increasing the ability of the hydrogen-bond formation of molecules, roughly stating, larger fraction of molecules would be involved within the somehow ordered regions as far as the molecular shapes are same. Since the structural ordering naturally develops at low temperatures [7,14,16], and since the ordering is expected to be of the short or medium range, the liquid structure as a snap shot is expected to be rather heterogeneous [1,[7][8][9][10][11]16,30].…”

Dielectric Relaxation and Crystallization of Ultraviscous Melt and Glassy States of Aspirin, Ibuprofen, Progesterone, and Quinidine

“…83 From optical microscopy studies, Hikima et al 24 found that crystal front grew into the glassy phase of o-terphenyl, at $220 K, that is, 20 K below its calorimetric T g of 240 K, and similar crystallization was observed for salol at 220 K about 1.6 K below its calorimetric T g of 221.6 K. Interestingly, crystallization of 2-salol was also followed by calorimetry 28 and it was found to continue for $5 days. Such localized motions also occur in the ultraviscous liquid state, 35 and Power and Vij 30 have found that D-sorbitol crystallizes most rapidly in the Donth temperature region, that is, the temperature at which the a-relaxation process, whose rate is far more sensitive to a temperature change than that of the JG process, develops and the number of molecules involved in the JG relaxation depletes.…”