隔热材料的湿度

　　Humidity of heat insulating material

　　材料的密度

　　Density of materials

　　密度是指单位体积的材料重量。隔热材料的密度是影响热导率的一个重要因素。隔热材料内部都存在一定的空隙，它是由材料骨架和空气间隙组成的。由于材料骨架的热导率比静止空气的要大的多，所以孔隙大的材料，其热导率较小。此外，材料的导热细嫩也与空隙的大小和形状有关，泡沫材料内含有无数封闭的微小气泡，气泡内空气的气流对流越微弱，隔热性能就越好。如果材料内的气泡较大或气泡之间的空气能相互流通时，热导率就越大。

　　Density is the material weight of unit volume. The density of heat insulation material is an important factor that affects the thermal conductivity. There are some gaps in the heat insulating material, which is composed of the material skeleton and the air gap. Because the thermal conductivity of the material skeleton is much larger than that of the static air, the material of the pore is larger, and the thermal conductivity of the material is smaller. In addition, material thermal conductivity and delicate with the size and shape of the voids, within the foam containing numerous closed small air bubbles, bubbles of air in the air convection is weak, heat insulation performance is better. Thermal conductivity is greater if the bubble in the material is larger or the air in the air bubbles in the air.