Upgrading of the joining area of vibration welded nanocomposites by modifying material, process and part geometry

热塑性聚合物由于其低密度和良好的可加工性，在包装和轻量化结构等许多应用中得到了应用。为了改善各种性能，如光学、导电或机械性能，正在添加增强材料。先前的研究表明，包括振动焊接在内的连接过程如何削弱（纳米）复合材料的机械性能（特别是韧性降低50%），而相比之下，非增强热塑性塑料则不会。主要原因是垂直于连接方向的填料和热塑性分子在流动中发生了取向变化，冷却后的形貌与注塑件不同。因此，连接区是焊接件的薄弱环节，非复合材料的潜力在均匀壁厚下无法发挥出来。该项目旨在解决这一问题。因此，将研究三种不同的方法：基于先前研究的负载路径联合碳纳米管增强，由于其刚度而显示出有利的取向，在连接过程后通过额外的热处理改变形貌，以及通过改变连接部分的几何形状来改变连接区域的流动方向和取向。

Thermoplastic polymers are being used in many applications such as packaging and light weight construction due to their low density and good processability. In order to improve various properties, such as optical, conductive or mechanical properties, reinforcement materials are being added. Previous investigations showed how joining processes, vibration welding included, weaken the mechanical properties (of (nano-)composites (especially the toughness by 50%) whereas in comparison they do not for non-reinforced thermoplastics. The main reason is the flow-induced change of orientation of filler and thermoplastic molecules perpendicular to the joining direction as well as a different morphology after cooling compared to injection molded parts. Therefore the joining area is the weakness of welded parts and the potential of nonocomposites can not be exploid at a uniform wall thickness.The project is amied to solve this issue. Therefore three different approaches will be investigated: load path allined reinforcement with carbon nanotubes based on previous investigations showing a beneficial orientation because of their stiffness, the change of morphology by an additional heat treatment after the joining process, and a change of flow direction and therefore orientation in the joining area by changing the joining part geometry.