水汽在涂层中的扩散传输行为

利用石英晶体微天平(QCM)为主要手段研究了水汽在醇酸清漆和聚氨酯清漆涂层中的扩散传输行为.水汽在上述涂层中的扩散符合Fick第二扩散定律.计算出了扩散系数D.用傅利叶变换红外光谱仪(FTIR)测定表明吸水前后涂层分子结构发生了变化.证明水分子和涂层分子发生了化学反应.

PERMEATION BEHAVOR OF WATER VAPOUR IN ORGANIC COATINGS OF ALKYD AND POLYURETHANE

The permeation behaviour of water vapour in coatings of alkyd and polyurethane varnish were studied by means of quartz crystal microbalance (QCM). QCM is a mass detector with a sensibility of nanogramme(10 -9 g) and can perform in situ on line test. The results show that the permeation of water vapour in the above coatings fits in the Fick's Second Law of Diffusion. The diffusion coefficient D is calculated. The molecular structure of the coatings before and after the absorption was examined by means of Fourier Transform Infrared Spectroscopy (FTIR). The subtraction results show that the molecular structure has changed, i.e. the water molecule reacts with the molecule of the coatings. Under the experimental condition (RH100%), the rate of the reaction is relatively faster than that of diffusion, the diffusion is the control step; so the total result is Fickian in nature.