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Viscosity at the liquidus temperature (TL), ηL, is a critical parameter for the design of new glasses, particularly for industrial glass production where crystallization must be suppressed. However, a direct viscometric determination of ηL for a glass‐forming system is difficult due to crystallization. Here we propose an alternative approach for determining ηL through differential scanning calorimetry (DSC). Specifically, DSC is used to measure both the viscosity curve and liquidus temperature of a glass‐forming system and then derive its ηL value. The ηL values determined using DSC are found to be in excellent agreement with those measured through viscometry. The DSC approach is applicable to various glass‐forming systems covering a wide range of fragilities and ηL values spanning over five orders of magnitude. Other advantages of this approach are its accuracy and small sample requirements. [ABSTRACT FROM AUTHOR]

• High temperature stability of mineral wool was quantified by hot stage microscopy. • The origin of its high temperature stability (HTS) was revealed by DSC and XRD. • The first-stage shrinking of mineral wool during heating is due to viscous flow. • Fiber crystallization is a key for the high temperature stability of mineral wool. Mineral wool, particularly stone wool, is a widely applied thermal insulation material that plays a critical role both in saving energy and in slowing the spread of fire in buildings owing to its high-temperature stability (HTS). However, so far there has been a lack of a universal method to accurately quantify HTS of mineral wool on a small scale. Here, we established a universal method, which is based on measuring the variation of the silhouette area of a cylindrical wool fiber pellet during heating by a hot-stage microscope. Using this method, we detected two main stages of shrinking: 1) the first-stage shrinking related to viscous deformation; 2) the second-stage shrinking caused by melting. Minimizing the first stage shrinking is the key to ensure the fire barrier role of stone wool. The origin of the HTS differences among different types of wool products was clarified by X-ray diffraction, differential scanning calorimetry and thermal expansion. [ABSTRACT FROM AUTHOR]

Stone wool is a widely used material for building insulation, to provide thermal comfort along with fire stability and acoustic comfort for all types of buildings. Stone wool waste generated either during production or during renovation or demolition of buildings can be recycled back into the stone wool melt production. This study investigates and compares the thermal response and melting behaviour of a conventional stone wool charge and stone wool waste. The study combines differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray diffraction (XRD). DSC reveals that the conventional charge and stone wool waste have fundamentally different thermal responses, where the charge experiences gas release, phase transition and melting of the individual raw materials. The stone wool waste experiences glass transition, crystallization and finally melting. Both DSC and HSM measurements indicates that the wool waste initiates melting at a lower temperature than the conventional charge. Also DSC measurements show that the wool waste requires less energy for heating and melting than the conventional charge, making stone wool waste recycling desirable both for environmental and for process purposes. [ABSTRACT FROM AUTHOR]