摘要
应用称重法、差示扫描量热法和腐蚀测试法研究固化的环氧树脂的吸水行为．实验结果表明，该树脂中的羟基改为乙酸基后可降低树脂的饱和吸水率，并增大水在树脂中的扩散能力．邻甲酚环氧树脂用乙酸线型酚醛酯树脂固化后所得的树脂（ＥＰＡ）在３０ ℃时饱和吸水率为０．８４％（质量分数），而用线型酚醛树脂固化所得的树脂（ＥＰ）的则为 １． ９７％；水在ＥＰＡ和ＥＰ中的扩散活化能分别为 ４０和 ４８ ｋＪ· ｍｏｌ－１．这可归因于乙酸基中的甲基的憎水性，降低了吸水率，却因乙酸基的弱相互作用增强了链的柔顺性，而有利于水在链空间中的扩散．ＥＰＡ涂层／金属铝界面的特殊结构降低了该界面的吸水率，从而提高了该涂层的防护性能．
A comparison of the effects of acetoxy and hydroxy groups on the water uptake into the cured epoxy resin was made using the gravimetric method, DSC and corrosion test. The experimental results show that the replacing of the hydroxy groups with acetoxy groups in the resin causes less water uptake, but increases the diffusibility of water in the resin. For example, at 30℃, the equilibrium water sorption of the o-cresol novolac epoxy resin cured with phenol novolac acetate resin (EPA ) is 0. 84% (mass fraction), while the epoxy resin cured with phenol novolac resin(EP) is 1. 97 %; the activation energies for diffusion of water in EPA and EP are 40 and 48 kJ. mol-1 respectively. The effects may be mainly due to the hydrophobic methyl group of the acetoxy groups. The methyl group prevents the uptake of water, but makes the acetoxy group more flexible, which causes water diffusion less difficult. Moreover, the results show that the unique structure of the interphase of the EPA coating/Al substrate even causes further less water uptake, and improves the effectiveness of corrosion protection for the coating accordingly.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2000年第5期813-815,共3页
Chemical Journal of Chinese Universities
基金
国家自然科学基金!(批准号: 29573100)
