Brittle-ductile transition of PP/POE blends in both impact and high speed tensile tests
Brittle-ductile transition of PP/POE blends in both impact and high speed tensile tests
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DOI：
10.1016/s0032-3861(03)00438-5
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发表时间：
2003-08-01
期刊：
影响因子：
4.6
通讯作者：
Zhang, YX
中科院分区：
文献类型：
--
作者：
Yang, JH;Zhang, Y;Zhang, YX
对聚丙烯（PP）/辛烯-乙烯共聚物（POE）共混物进行了冲击和高速拉伸实验，实验中实际应变速率为208/s。随着POE含量的增加，PP/POE共混物在冲击和高速拉伸试验中都出现了脆韧转变（BDT）。当拉伸PP/POE共混物时，随着拉伸速度的降低，BDT也发生。详细分析了缺口冲击试样的冲击变形。在冲击试验中，缺口冲击试样的大部分应变载荷是由缺口尖端附近狭窄区域的变形来承担的。由于变形区存在拉伸速度梯度，变形区的微单元以两种方式变形：高速拉伸变形和剪切变形。在冲击试验开始时，缺口尖端处的应变速率几乎达到6000/s。在增韧橡胶塑料中，由于橡胶颗粒的气穴现象，剪切变形大大降低。因此，在缺口尖端附近的狭窄区域，冲击变形实际上是一种高速拉伸变形。冲击和高速拉伸试验中的BDT具有相同的机理。塑料的缺口敏感性实质上是塑料的拉伸速度敏感性。(C)2003爱思唯尔科技有限公司。保留所有权利。
Polypropylene (PP)/octene-ethylene copolymer (POE) blends were studied in both impact and high speed tensile tests, in which the practical strain rate was 208/s. With the increase of the POE content, brittle-ductile transition (BDT) of PP/POE blends occurred in both the impact and high speed tensile tests. BDT also occurred with the decrease of the tensile speed when any of the PP/POE blends was drawn. The impact deformation of the notched impact samples was analyzed in details. Most of the strain loading of the notched impact samples is taken by the deformation of the narrow region near the notch tip in impact tests. The microunits of the deformation region deform in two methods: high speed tensile deformation and shear deformation because of the tensile speed gradients in the deformation region. At the beginning of impact tests, the strain rate at the notch tip reaches almost 6000/s. In rubber toughened plastics, the shear deformation decreases greatly because of the rubber particle cavitation. Thus, the impact deformation is really a high speed tensile deformation at the narrow region near notch tips. The BDTs in both impact and high speed tensile tests share the same mechanism. The notch sensitivity of plastics is essentially the tensile speed sensitivity of plastics. (C) 2003 Elsevier Science Ltd. All rights reserved.