The results showed that the fracture surface of the modified systems displayed tough fracture features, markedly different from that of the unmodified epoxy resin system.

结果表明，增韧后材料的断面形态明显不同于未改性体系的形态，试样冲击断裂面形态具有明显的韧性断裂特征。

youdao

For the UPR with greater brittleness, the brittle-tough transition was observed only when the toughness of the resin was characterized by fracture toughness at a slower loading rate.

对于脆性较大的UPR，只有在采用加载速度较慢的断裂韧性来表征其韧性时，方能观察到这一脆韧转变现象。

youdao

The impact fracture surface showed a tough morphology for POM/NBR/Novolak blends and brittle one for POM/NBR blends.

断裂形貌考察表明，POM/ NBR共混物的断裂面呈脆性断裂特征；

youdao