无溶剂环氧涂层在不同流速的3.5% NaCl溶液中的吸水性研究  

Water Absorption Behavior of Solvent-Free Epoxy Coating in 3.5% NaCl Solution

作　　者：赵洪涛[1] 陆卫中[1] 李京[1] 

机构地区：[1]中国科学院金属研究所,辽宁沈阳110016

出　　处：《材料保护》2016年第10期35-41,共7页Materials Protection

基　　金：中国科学院A类战略性先导科技专项(XDA13040500)资助

摘　　要：目前对于水在防腐蚀涂层中的传输研究大都集中在静态浸泡条件下,且大部分都基于有机溶剂涂层,鲜见流速对无溶剂涂层在海水中传输行为的影响研究。在60℃的3.5%NaCl溶液中以3种无溶剂环氧防腐蚀涂层自由膜为研究对象,利用称重法(GM)研究了不同流速下水在涂层中的扩散行为,采用差示扫描量热法(DSC)和近红外光谱技术(NIR)研究了水的存在形式以及不同类型水的含量变化。结果表明:胺类固化环氧粉末涂层和酚醛固化环氧粉末涂层在试验流速范围内、酚醛胺固化无溶剂环氧液体涂层在较低流速范围内,水在涂层中的扩散符合FickⅡ模型,而在4 m/s的高流速下,水在无溶剂环氧液体涂层中的扩散偏离FickⅡ模型;随着流体流速增加,3种涂层自由膜的饱和吸水量增加,水在涂层自由膜中的扩散系数变大,涂层自由膜吸水达到饱和的时间减少;水在无溶剂环氧涂层自由膜中有3种存在形式:不形成氢键的水分子(S0)、形成1个氢键的水分子(S1)和形成2个氢键的水分子(S2)。随着流速的增加2种环氧粉末涂层自由膜中S0、S1和S2的含量均增加,水对自由膜的塑化作用增强;而无溶剂环氧液体涂层由于水分子同未反应的环氧基团发生开环反应,使高分子链进一步地交联,导致自由膜内水分含量反而减小。Three kinds solvent-free epoxy coaling served as the object of study at 60 ℃,the diffusion behavior of water through coatings in different flow velocities of 3.5%NaCl solution was investigated by Gravimetric Method(GM),and the types and content of water existing in free films under different flow velocities were studied by differential scanning calorimetry(DSC) and near infrared speclroscopy(NIR).Results showed that for amine-cured and phenolic aldehyde-cured epoxy powder coating free film within the scope of the test flow velocity,and phenolic aldehyde amine-cured liquid epoxy coating free film at lower flow velocity,the diffusion behavior of water through coating at different flow velocities agreed well with Fick II diffusion model.However,at 4 m/s flowing condition,the diffusion behavior of water through coating departed from Fick II diffusion model.With the increase of flow velocity,saturation of 3 kinds of free films increased,and the diffusion coefficient of water in solvent-free epoxy coating ascended,as well as the required time for coatings absorbing water to saturated state became shorter.Furthermore,three types of water molecules,termed as S_0,S_1 and S_2 were detected in three kinds of free film,which referred to water molecules without hydrogen bond,with one hydrogen bond,with two hydrogen bonds,respectively.With the increase of flow velocity,content of S_0,S_1 and S_2-type of water existing in amine-cured and phenolic aldehyde-cured epoxy powder coating free film increased,and the plasticizing effect of water for these two free films became stronger.Otherwise,for phenolic aldehyde amine-cured liquid epoxy coating free film,as the flow velocity increased,the reaction between water molecules and unreacted epoxy group became easier,leading to further crosslinking of polymer chain and reduction of water content in free film.

关 键 词：无溶剂环氧防腐蚀涂层 3.5%NaCl溶液 流速 吸水性 

分 类 号：TG174.4[金属学及工艺—金属表面处理]