Torchinsky Darius H, Johnson Jeremy A, Nelson Keith A
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Chem Phys. 2009 Feb 14;130(6):064502. doi: 10.1063/1.3072476.
We present an impulsive stimulated scattering test of the "shoving model" of the glass transition and of the correlation between the fragility index and the ratio of instantaneous elastic moduli of eight supercooled liquids. Samples of triphenyl phosphite, DC704 (tetramethyl tetraphenyl trisiloxane), m-fluoroaniline, Ca(NO(3))(2)4H(2)O, diethyl phthalate, propylene carbonate, m-toluidine, phenyl salicylate (salol), 2-benzylphenol, and Santovac 5 (5-phenyl 4-ether), were cooled to their respective glass transition temperatures and the elastic moduli directly measured at the highest accessible shear frequencies. The shear modulus was then measured every 2 K as deeply as permitted into the liquid state for all liquids except propylene carbonate. Our results, in conjunction with dynamical relaxation data for these liquids obtained from the literature, lend credence to the notion that the dynamics of the glass transition are governed by the evolution of the shear modulus but do not suggest a strong correlation between the fragility index and the ratio of the elastic moduli.
我们展示了对玻璃化转变的“推挤模型”以及八种过冷液体的脆性指数与瞬时弹性模量之比之间相关性的脉冲受激散射测试。亚磷酸三苯酯、DC704(四甲基四苯基三硅氧烷)、间氟苯胺、Ca(NO(3))(2)4H(2)O、邻苯二甲酸二乙酯、碳酸丙烯酯、间甲苯胺、水杨酸苯酯(萨罗)、2-苄基苯酚和Santovac 5(5-苯基4-醚)的样品被冷却至各自的玻璃化转变温度,并在可达到的最高剪切频率下直接测量弹性模量。除碳酸丙烯酯外,对所有液体,然后在允许的深度范围内,每隔2 K测量一次剪切模量直至液态。我们的结果,结合从文献中获得的这些液体的动力学弛豫数据,支持了玻璃化转变动力学受剪切模量演变支配的观点,但并未表明脆性指数与弹性模量之比之间存在强相关性。