摘要：In pressurized glass-forming systems, the apparent (changeable) activation volume V a (P) is the key property governing the previtreous behavior of the structural relaxation time (τ) or viscosity (η), following the Super-Barus behavior: [Formula: see text], T = const. It is usually assumed that V a (P) = V # (P), where [Formula: see text] or [Formula: see text]. This report shows that V a (P) ≪ V # (P) for P → P g , where P g denotes the glass pressure, and the magnitude V # (P) is coupled to the pressure steepness index (the apparent fragility). V # (P) and V a (P) coincides only for the basic Barus dynamics, where V a (P) = V a = const in the given pressure domain, or for P → 0. The simple and non-biased way of determining V a (P) and the relation for its parameterization are proposed. The derived relation resembles Murnaghan - O'Connel equation, applied in deep Earth studies. It also offers a possibility of estimating the pressure and volume at the absolute stability limit. The application of the methodology is shown for diisobutyl phthalate (DIIP, low-molecular-weight liquid), isooctyloxycyanobiphenyl (8*OCB, liquid crystal) and bisphenol A/epichlorohydrin (EPON 828, epoxy resin), respectively.
