A direct test of the correlation between elastic parameters and fragilityof ten glass formers and their relationship to elastic modelsof the glass transition

摘要

We present an impulsive stimulated scattering test of the "shoving model" of the glass transition andof the correlation between the fragility index and the ratio of instantaneous elastic moduli of eightsupercooled liquids. Samples of triphenyl phosphite, DC704 (tetramethyl tetraphenyl trisiloxane),m-fluoroaniline, Ca(NO3)2.4H20, diethyl phthalate, propylene carbonate, m-toluidine, phenylsalicylate (salol), 2-benzylphenol, and Santovac 5 (5-phenyl 4-ether), were cooled to their respectiveglass transition temperatures and the elastic moduli directly measured at the highest accessible shearfrequencies. The shear modulus was then measured every 2 K as deeply as permitted into the liquidstate for all liquids except propylene carbonate. Our results, in conjunction with dynamicalrelaxation data for these liquids obtained from the literature, lend credence to the notion that thedynamics of the glass transition are governed by the evolution of the shear modulus but do notsuggest a strong correlation between the fragility index and the ratio of the elastic moduli.