环氧树脂/聚氨酯共混体系相行为研究

利用小角光散射 (SALS)技术实时记录了环氧树脂 聚氨酯共混体系在固化过程中的相行为发展情况 ,得到了表征共混体系相区结构尺寸大小的相关距离ac 和表征体系均匀程度的均方介电常数涨落 η2 ,讨论了等温固化条件下 ,环氧树脂 聚氨酯共混体系的相区大小随时间的变化规律 .实验结果表明 ,环氧树脂 聚氨酯共混体系的固化过程是典型的反应诱导相分离的过程 .相分离初期 ,符合Cahn的线性理论 ;随着固化时间的延长 ,相区由小变大 ,约至反应开始后 3 2 1 0s,相分离趋于平衡态 ,相区尺寸趋于稳定

STUDY ON THE PHASE BEHAVIOR OF EP/TPU BLENDS BY USING THE SMALL ANGLE LIGHT SCATTERING METHOD

Elastomer-modifying is often used to improve the mechanical properties of epoxy resins,and the epoxy resin(EP)/thermoplastic polyurethane(TPU) is a fairly effective system.In this article the phase behavior of EP/TPU blends was investigated by time-resolved small angle light scattering (SALS) analysis.The correlation distance ( a c) and mean square dielectric constant fluctuation ( 2 ) of EP/TPU blends were calculated.Evolutions of the domain size in EP/TPU blends were discussed under the isothermal curing condition.The results showed that the cured process of EP/TPU was a typical spinodal decomposition and can be well described by Cahn-Hilliard linearized theory at the early stage.With the cure development,the domains grew up and kept constant after 60?min.During the early blend cure process,the correlation distance ( a c) and mean square dielectric constant fluctuation ( 2 ) of EP/TPU blends increased rapidly,from 0 to 1 00 and 0 to 118,respectively,if the experimental time was from 145?s to 1080?s.After that,the domains of the blends began to coalesce resulting in the decrease of 2 and increase of a c,which will keep constant after 3210 s when a c and 2 are 1 30 and 32,respectively.