Development of the glassy state of benzophenone and effect of heating rate from the glassy state on solidification

摘要

Benzophenone supercools to a glass when cooled to - 100 deg C. In fact, it is difficult to freeze benzophenone on cooling. In this investigation, the effect of cooling rate and the minimum cooling rate to obtain benzophenone as a glass is determined.From the glassy state, the influence of heating rate on the solidification temperature of benzophenone is determined. When heated at 3 deg C/min, solidification starts at about - 29 deg C. Upon additional heating, elting usually starts at about + 24 deg C, which is 23 deg C lower than the solid equilibrium structure melting temperature of 47 deg C. Occasionally the solid that forms at about - 29 deg C undergoes a solid state phase transformation at about + 22 deg C, when heated at 3 deg C/min. If this solid state phase transformation occurs, then the solid benzophenone starts to melt at 47 deg C. When solid benzophenone with the equilibrium structure is cooled to - 100 deg C, no solid state phase trasformation occurs. It appears that the structure that solidifies at - 29 deg C is metastable.