| 摘要 |
Method of measuring the water-vapour diffusion properties of porous sheet materials in which one or more layers of the specimen is fixed in front of an opening in a measuring chamber. The opening is sealed with a water-coated PTFE membrane. The measuring chamber and the specimen are placed in a climatic chamber filled with a standard atmosphere and the decrease in weight of the measuring chamber is determined at certain time intervals. From the values of the decrease in weight DELTA G of the measuring chamber obtained after the test time intervals DELTA t, auxiliary characteristic values Ret<*>n are calculated using the equation <IMAGE> and from the latter the regression line Ret<*> = Ret . n + Ret0, where n is the number of specimen layers, is calculated and from this the required specific moisture transmission resistance Ret is derived. The method is carried out with a largely automated device individually designed for the method.
|
