咪唑封端聚氨酯予聚体改性环氧树脂E-51/双氰双胺固化体系性能研究

以聚丙二醇PPG10 0 0、甲苯二异氰酸酯 (TDI)、咪唑为原料 ,合成了咪唑封端的聚氨酯予聚体 ,简称扩链脲TIEU .利用DSC、粘弹谱仪、冲击试验机及扫描电镜 (SEM)等手段对TIEU改性的环氧树脂E 5 1/双氰双胺(dicy)固化体系的反应活性、动态力学行为、冲击性能、断裂面形态结构进行了系统研究 .实验结果表明 ,改性后的E 5 1 dicy体系反应活性明显提高 ,固化反应的表观活化能由未改性体系的 131kJ mol降至 75～ 80kJ mol.与咪唑促进体系比较结果显示 ,两种固化反应的促进机制具有一定的差异 .另外与未改性体系相比 ,经过改性的环氧树脂体系冲击强度提高 2～ 3倍 ,而玻璃化温度和模量基本不变 ,冲击断面呈韧性断裂

STUDIES ON THE PROPERTIES OF E-51/DICYANDIAMIDE SYSTEM MODIFIED WITH IMIDAZOLE-TERMINATED CHAIN-EXTENDED UREA

A chain extended urea(TIEU) containing flexible spacer was synthesized from polypropylene glycol PPG1000,toluenediisocyanate (TDI) and imidazole.The reactive activity,dynamic mechanical behavior,impact property and morphology of the curing systems were systematically investigated by DSC,viscoelastic spectroscopy,impact tester and SEM,respectively.Results show that the curing activity of modified E 51/dicy system was so greatly enhanced that the apparent activation energy of curing reaction is reduced from 131?kJ/mol for the unmodified system to 75～80?kJ/mol.The curing reaction mechanism of E～51/dicy system accelerated by TIEU was a little different from that of the system accelerated by imidazole.The impact stength of the curing systems modified with TIEU was 2～3 times higher than that of the unmodified system,while the glass transition temperature and modulus were little changed.and the fracture surfaces of the modified systems displayed tough fracture feature.