Impact of dynamic stretching exponent on the correlation between liquid fragility and nonexponentiality at the glass transition

The presence of large scatter in linear response data has cast doubt on the existence of an inverse correlation between liquid fragility and nonexponentiality, as originally proposed by Böhmer et al (1993 J. Chem. Phys. 99 4201). We present a model for the temperature dependence of the stretching exponent based on the Mauro-Yue-Ellison-Gupta-Allan model for supercooled liquid viscosity and discuss the factors impacting the relationship between fragility and the stretching exponent at the glass transition. The proposed model exhibits distinct advantages over previous models in terms of interpretability and limit behaviors for the temperature dependence.