DISPERSION MORPHOLOGY AND FRACTURE MECHANISM OF NYLON 6 ALLOY
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摘要: 利用低真空扫描电镜和高真空扫描电镜及偏光显微镜对尼龙-6/热塑性聚酰胺弹性体合金的分散形态和破坏形貌观察照相, 结果表明: (1) 在三轴应力作用下, 尼龙-6 合金试样U 型缺口前部塑性区域由微细程度和密度均不等的银纹组成, 银纹结构是空洞, 空洞是TPA E 粒子的变形和破坏所致, 空洞的变形加剧母体尼龙-6 的颈缩化; (2)尼龙-6 合金因塑性区域内的空洞化和空洞的变形及空洞之间区域的颈缩和纤维化, 有效地吸收了破坏能量, 使塑性约束得到缓解, 促进了平面应变状态向平面应力状态转变, 最终呈半韧性或韧性破坏; (3) 低真空扫描电镜观察照相既能反映TPA E 粒子的变形程度, 又能反映分散相粒子的破坏过程和空洞大小。Abstract: Nylon 6 shows low impact strength values. By adding thermoplastic polyamide elastomers(TPAE), Nylon 6 alloy can obtain high impact strength values. PLM and SEM observations of the fracture surfaces and deformed regions beneath the fracture surfaces revealed that the fracture process of Nylon 6 was brittle, which was originated from the plastic constraint at the notch tip. The fracture of the alloy was also caused by the plastic constraint at the notch tip. However, the plastic deformation zone at the notch tip was composed of many voids and partially elongated fibrils, and this absorbed the impact energy. The plastic deformation was enhanced by the transition of the stress state from plane strain to plane stress. The final fracture occurred from the notch tip connecting voids in the plastic deformation zone.
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Keywords:
- Nylon 6 /
- thermoplastic polyamide elastomers /
- alloy /
- void /
- plastic constraint
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