Thermobaric history as a tool to govern properties of glasses: case of dipropylene glycol

Abstract

The elastic properties of high- and low-pressure glasses of dipropylene glycol were determined for the first time under conditions of isothermal compression up to 1 GPa at 77 K and isobaric heating of 77–300 K at 0.05 GPa and 1 GPa. A strong dependence of the elastic properties of glasses on their thermobaric history has been revealed: glasses obtained at high pressure have not only higher densities (3.9%), but also noticeably higher elastic moduli. This effect is especially pronounced in the shear modulus: high-pressure glass has a 30% higher shear modulus than low-pressure glass. The behavior of elastic moduli during the glass-to-liquid transition also depends on the thermobaric history. Glass produced at low pressure but heated at high pressure has anomalous temperature dependences of the elastic moduli. Heating dipropylene glycol glasses at different pressures allowed us to refine the T_g(P) dependence.