X-ray photo-electron spectroscopic studies of cryogenic and plasma surface-treated z-pins
X-ray photo-electron spectroscopic studies of cryogenic and plasma surface-treated z-pins
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DOI：
10.1177/0021998317691811
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发表时间：
2017-04
影响因子：
2.9
通讯作者：
A. Knopp;G. Scharr
中科院分区：
文献类型：
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作者：
A. Knopp;G. Scharr
复合材料的力学性能主要取决于其组成部分之间的载荷传递。特别是，由预浸渍纤维（prepreg）制成的具有三维z-pin增强的纤维增强聚合物的断裂性能会受到pin与层压板之间界面特性的影响。采用x射线光电子能谱（XPS）分析和扫描电镜（SEM）研究了未经处理、低温处理和等离子体表面处理的z-pin，以确定表面处理对pin表面化学成分、官能团形成和形貌的影响。通过拉出试验研究了表面处理对桥接力的影响，桥接力对z-钉钉层合板的分层韧性有显著影响。指出低温处理不能导致z针表面氧或氮官能团的增加。然而，由于表面粗糙度的增加，拔出力可能会增加。然而，通过等离子体处理，可以达到氧和氮的功能化。可以确定所有血浆处理都增加了O/C比率。综上所述，等离子体处理可以产生氧官能团。这些基团能够在z-pin表面和大块材料之间建立共价键，从而可以在pin和层压板之间更好地传递载荷，从而获得更高的断裂性能。由于等离子体处理后的表面粗糙度更高，引脚和层压板之间的附着力得到了改善，联锁效应也得到了增强，从而增加了拉拔力。
The mechanical properties of composite materials are primarily dependent on the load transmission between their components. Especially, the fracture performance of a fibre-reinforced polymer made of a preimpregnated fibres (prepreg) with a three-dimensional z-pin reinforcement can be influenced by the interface characteristics between pins and laminate. X-ray photo-electron spectroscopic (XPS) analysis and scanning electron microscopic (SEM) studies of untreated, cryogenic and plasma surface-treated z-pins were carried out to determine the effect of surface treatments on chemical composition, formation of functional groups and topography of pin surface. Pullout tests were conducted to investigate the impact of a surface treatment on the bridging forces, which have significant influence on delamination toughness of a z-pinned laminate. It was pointed out that a cryogenic treatment cannot lead to an increase of oxygen or nitrogen functional groups at the z-pin surface. Nevertheless, the pullout forces can be increased which are caused by an increased surface roughness. However, with a plasma treatment, an oxygen and nitrogen functionalization can be reached. An increase of the O/C ratio with all plasma treatments can be determined. Summarizing the results, it can be shown that oxygen functional groups can be generated by a plasma treatment. These groups are able to establish covalent bonds between z-pin surface and bulk material, which can lead to a better load transmission between the pins and laminate and thus to higher fracture properties. The increased pullout forces result from a combination of improved adhesion between pins and laminate and increased interlocking effects, due to the higher surface roughness after plasma treatment.