环氧树脂/聚氨酯共混体系相行为研究

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

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 。

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 ( (eta) over bar (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 ((eta) over bar (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 (eta) over bar (2) and increase of a(c), which will keep constant after 3210 s when a(c), and (eta) over bar (2) are 1.30 and 32, respectively.