The significance of the hydrophobicity of insulation materials to architecture
2019-04-19 11:16:55 From: Tradematt-Aerogel
When the insulation material is in contact with water, some materials can be wetted by water, while some materials cannot be wetted by water. For the two phenomena, the former is hydrophilic and the latter is hydrophobic.
If a thermal insulation material is not well watered or water repellent, its defects will be fatal.
First, when the insulating material contains water, the thermal conductivity is drastically increased, so that the insulating layer is virtually ineffective. The common feature of thermal insulation materials is that they are lightweight, loose, porous or fibrous, and block the heat conduction by air that does not flow inside. In particular, the pores of many inorganic thermal insulation materials are not completely closed-cell structures. The material inevitably absorbs water in a humid environment, and the thermal conductivity of water (O.5815 W/m.k) is about the thermal conductivity of static air (O). .0233W/m.k) is 25 times. Therefore, when the ambient humidity increases, the equilibrium moisture content of the material increases, and the thermal conductivity of the thermal insulation material will rise sharply. Studies have shown that the thermal insulation material with a thermal conductivity of 0.03 W/m·K increases the thermal conductivity by 25% after 1% moisture absorption, and increases by a factor of multiple. If the water is condensed into ice, since the thermal conductivity of the ice is about four times that of water, the thermal conductivity of the material will be further increased, and eventually the thermal insulation properties of the material may be completely lost.
Secondly, when the cold weather comes in winter, the high water absorption rate insulation material will be seriously damaged after freezing and thawing. When the temperature is negative, the water in the pores will form ice, and the volume will expand, which will exert a force on the tissue around the hole and will correspond to a relative displacement, which will enlarge the size of the hole. After several freeze-thaw cycles, the size of the pores will become larger and larger, and there will be a repeated load, and the resistance of the tissue around the pores becomes weaker. After many actions, cracks appear and eventually collapse. From a macroscopic point of view, it must be that the insulation system has cracked and fallen off.
If the insulation material has a high water content and the selected surface glue is also lacking in water repellency, the water vapor will pass through the insulation system without hindrance. In the wet weather, the insulation layer absorbs water, and the weather and water vapor are discharged to the outside to form a pan-alkali phenomenon, and the outer surface layer is formed.
In summary, the building insulation is to put on a cotton quilt for the building. This cotton tampon can not absorb water except for heat preservation. The aerogel insulation products produced by Tradematt are flexible water-repellent materials, which have the advantages of water resistance and crack resistance. After 80 times of high temperature-watering cycle and 30 times of heating-refrigeration cycle, there is no blistering of the finish layer. The hollow drum and shedding phenomenon did not produce water seepage cracks, and the performance of all aspects of the products was superior to the national standard.