含聚醚间隔链的扩链脲改性环氧树脂/双氰双胺固化体系性能研究

合成了一系列含不同分子量聚环氧丙烷 (PPG)柔性间隔链的扩链脲 ,系统考察了扩链脲改性环氧树脂E 5 1/双氰双胺 (dicy)固化体系的固化反应活性、动态力学行为、冲击性能和断裂面形态结构 ,并对体系的冲击性能、形态结构与动态力学行为之间的关系进行了探讨 .结果表明 ,改性体系固化反应活性明显提高 ,固化反应表观活化能降低 ,固化反应峰顶温度从 190℃降低至 14 0℃ ,固化反应的表观活化能由 14 5 5kJ/mol降至 70～ 80kJ mol;改性体系冲击强度明显提高 ,其中所含PPG柔性链分子量为 10 0 0的扩链脲改性的E 5 1/dicy体系冲击强度较未改性的E 5 1/dicy体系提高了 8倍 ,其冲击试样断裂面的形态具有明显的韧性断裂特征 ,微观两相网络结构的存在导致了改性体系冲击强度显著提高

STUDIES OF THE PROPERTIES OF EPOXY RESIN/DICYANDIAMIDE CURING SYSTEM TOUGHED BY CHAIN-EXTENDED UREA CONTAINING FLEXIBLE SPACER

A series of extended chain ureas(U i) containing polypropylene glycol(PPG) spacers with different molecular weight were synthesized.The reactive activity,dynamic mechanical behavior,impact property and morphology of the U i modified E 51/dicy curing system were investigated systematically,the relationships among the dynamic mechanical behavior,impact strength and morphology were also discussed.Results show that the curing activity of modified E 51/dicy curing system was so greatly enhanced that the curing reaction peak temperature decreased from 190 to 140℃, and the apparent activation energy of curing reaction is reduced from 145 5 kJ/mol to 70～80 kJ/mol.The impact strength of the U i modified curing system was increased significantly,E 51/dicy/U 1(extended chain urea containing PPG flexible spacer with molecular weight 1000)system was 8 times higher than that of the unmodified E 51/dicy curing system,the fracture surfaces of the E 51/dicy/U 1 systems displayed tough fracture feature,which is very different from that of the unmodified system.There exist two phase microstructure for the modified curing systems.This leads to the significant increasing in impact strength.