Mechanism rock wool board, a mineral fiber product made from natural minerals such as basalt and dolomite, is melted at high temperatures, then centrifugally formed into fibers, solidified, and cut. The relationship between thermal conductivity and density is not a simple linear relationship, but rather a nonlinear, complex relationship influenced by multiple factors. This characteristic stems from the unique fiber structure and distribution of closed air pores within mechanism rock wool board, as well as the material's inherent regulation of heat conduction paths.
From a microscopic perspective, mechanism rock wool board's thermal conductivity is primarily determined by the number and size of closed air pores between fibers. When the density of mechanism rock wool board is low, the fibers are loosely arranged, with larger interfiber gaps and fewer closed pores. Heat is easily transferred within the material through air convection and solid heat conduction, resulting in a higher thermal conductivity. As density increases, the contact between fibers becomes closer, the number of closed pores increases significantly, and air, a poor conductor of heat, is trapped within the fiber network, effectively blocking the heat convection path. Furthermore, the thermal conductivity of air within the closed pores is much lower than that of solid fibers, causing the thermal conductivity of mechanism rock wool board to gradually decrease. However, this downward trend is not indefinite. When the density of mechanical rock wool board increases to a certain level, the number of closed pores between fibers continues to increase, but their size gradually decreases. The heat transfer mode begins to shift from primarily air convection to primarily solid heat conduction. At this point, despite the increase in the number of closed pores, the proportion of solid fibers increases, and the effect of solid heat conduction is enhanced, resulting in a slower decrease in the thermal conductivity. If the density increases further, the contact between fibers becomes too close, the number of closed pores decreases, and their size further decreases. Solid heat conduction becomes dominant, and the thermal conductivity of mechanical rock wool board gradually increases with increasing density.
The fiber diameter and arrangement of mechanical rock wool board also affect the relationship between thermal conductivity and density. Finer fiber diameters and uniform arrangement promote more and smaller closed pores, resulting in lower thermal conductivity at the same density. Conversely, thicker fibers or irregular arrangement may lead to uneven distribution of closed pores, affecting the blocking effect of heat conduction paths and causing fluctuations in the relationship between thermal conductivity and density.
In practical applications, the relationship between the thermal conductivity and density of mechanical rock wool board must also consider environmental factors. For example, humidity fluctuations may cause the fibers to absorb moisture, altering the air conditions within the closed pores and thus affecting thermal conductivity. Temperature fluctuations may cause thermal expansion or contraction of the fibers, changing the inter-fiber contact state and closed pore size, dynamically affecting thermal conductivity. These environmental factors, combined with density, result in a more complex, nonlinear variation in the thermal conductivity of mechanical rock wool board in actual use.
Understanding this nonlinear relationship between thermal conductivity and density is crucial for the production and application of mechanical rock wool board. In building insulation projects, the appropriate density of mechanical rock wool board must be selected based on specific application requirements, such as mechanical properties, noise reduction and sound insulation, and fire rating, to achieve optimal insulation performance while meeting functional requirements. Excessively high density may increase thermal conductivity and weaken insulation effectiveness, while excessively low density may affect the material's mechanical strength and durability. Therefore, achieving a balance between density and thermal conductivity through scientific design and process control is key to the application of mechanical rock wool board.
