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加工性而被用于许多应用中，例如包装和轻质结构。为了改善各种性能，例如光学、导电或机械性能，正在添加增强材料。以前的研究表明，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，它们不会影响非增强热塑性塑料。主要原因是流动引起的填料和热塑性分子垂直于连接方向的取向变化以及冷却后与注塑成型部件相比的不同形态。因此，连接区是焊接件的薄弱环节，在壁厚均匀的情况下，纳米复合材料的潜力无法充分发挥，本课题旨在解决这一问题。因此，将研究三种不同的方法：负载路径与碳纳米管对齐的增强基于先前的研究，由于其刚度显示出有益的取向，在连接过程后通过额外的热处理改变形态，以及通过改变连接部件的几何形状改变流动方向，从而改变连接区域的取向。

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.