A microscopy study of the transition from yielding to crazing in polypropylene
A microscopy study of the transition from yielding to crazing in polypropylene
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DOI：
10.1002/pen.10936
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发表时间：
2002-01-01
影响因子：
3.2
通讯作者：
Huétink, J
中科院分区：
文献类型：
--
作者：
Dijkstra, PTS;Van Dijk, DJ;Huétink, J
用扫描电子显微镜研究了聚丙烯的变形机制与应变速率的关系。在50 ℃的温度和10（-4）到90 s（-1）的应变速率下对注塑的狗骨状试样进行拉伸测试。随着应变速率的增加，观察到从冷拔和颈缩到几乎均匀变形的逐渐过渡。该转变的特征在于断裂后的强弹性反冲。在点上的（λ）= 90 s（-1）时，弹性恢复具有其最大值，为断裂应变的70%（λ = 0.3）。死后，使用高锰蚀刻样品在颈部外的小应变下研究形态。宏观行为的转变与变形机制的变化相吻合。在低应变率下屈服是主要机制，而在dot = 90 s（-1）时发现均匀空洞。一个相关性的建议之间的失败链滑动层内和发生的空洞。导致球晶中的明显的空隙图案。
The deformation mechanisms in polypropylene as a function of strain rate have been studied by scanning electron microscopy. Injection molded, dogbone specimens were tested in tension at a temperature of 50degreesC and strain rates from 10(-4) to 90 s(-1). With increasing strain rate a gradual transition from cold drawing and necking to nearly homogeneous deformation was observed. The transition is characterized by a strong elastic recoil after fracture. At (epsilon) over dot = 90 s(-1), the elastic recovery has its maximum value of 70% of the strain at break (epsilon = 0.3). The morphology was studied post mortem at small strains outside the neck using permanganically etched samples. The transition in the macroscopic behavior was found to coincide with a change in the deformation mechanism. Whereas yielding is the dominant mechanism at low strain rates, homogeneous voiding is found at (epsilon) over dot = 90 s(-1). A correlation is suggested between the failure of chain slip within the lamellae and the occurrence of voiding. leading to distinct voiding patterns in the spherulites.