New scaling paradigm for dynamics in glass-forming systems

The lack of ultimate scaling relations for previtreous changes of the primary relaxation time or viscosity in glass-forming systems constitutes the grand fundamental challenge, also hindering the development of relevant material engineering applications. The report links the problem to the location of the previtreous domain remote from a hypothetical divergence, hidden in the solid glass state. As the solution, the distortions-sensitive and linearized derivative-based analysis is proposed. It is implemented to scaling relations being checkpoints of basic glass transition models: free volume, entropic, critical-like, avoided criticality, kinetically constrained, or Ising model related. For discussed scaling relations, alternative formulations based on fragility, the semi-universal metric for previtreous dynamics, are presented. The alternative approach based on the activation energy index, showing its relative changes, is also presented. Derived relations are validated for the primary relaxation time experimental data in the homologous series of polyols, from glycerol to sorbitol. Only two scaling equations passed the exam: MYEGA, the recent 'activation and critical' (AC), and their pressure counterparts. The report shows that the coherent picture linking (i) the Super-Arrhenius for the temperature path, (ii) the Super-Barus behavior for the pressure path, and anomalous changes detected on compessing, namely (iii) inflection, and (iv) viscosity decrease or speeding for relaxation time, is possible.The report also shows the limited reliability of the so-called Stickel analysis and its pressure counterpart used for detecting the dynamic crossover in the previtreous domain.

Automated summary

The report proposes a distortions-sensitive and linearized derivative-based analysis to address the lack of ultimate scaling relations for previtreous changes in glass-forming systems. The method is capable of validating scaling relations in various glass transition models and provides alternative formulations based on fragility. The report also demonstrates the successful validation of the derived relations using experimental data from a homologous series of polyols.