Quantification of High Temperature Stability of Mineral Wool for Fire-safe Insulation

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.