聚芳醚酮高温长时间下的断裂行为3．韧性－脆性断裂转变

THE FRACTURE BEHAVIOR OF POLY (PHENYLENE ETHER KETONE) AT ELEVATED TEMPERATURE FOR LONG TERMS 3.DUCTILE-BRITTLE TRANSITION

研究了聚芳醚酮（ＰＥＫ－Ｃ）在２００℃下长时间放置过程中拉伸断裂行为的变化．通过应力－应变实验、断面形貌观察及去老化现象的研究证实，２００℃下长时间放置后的ＰＥＫ－Ｃ的拉伸断裂行为，发生韧性－脆性转变，发生这一转变的时间约在５８９小时左右．伴随１９９℃下的拉伸过程中出现的去老化现象，决定于材料发生剪切屈服形变的能力，与韧性－脆性断裂行为转变有着本质的联系．

The ductile-brittle transition(DBT)of poly (phenylene ether ketone)due to long-term retaining at temperature of 200℃ has been studied by tensile experiment,scanning electron microscopy and differential scanning calorimetry measurements. The DBT can be considered as competition between fracture mechanisms of crazing and that of shear yielding.It is found that the DBT of PEK-C due to long-term retaining at 200℃ occurs at about 589 retaining hours.It is shown from tensile experiment that the deaging phenomena was observed, and it only depends on the shear deformation and has intrinsic relationship with DBT.