Investigation of the Orientation Behaviour of Liquid Crystalline Polymers in Fused Deposition Modeling

增材制造允许在没有模具的情况下使用各种类型的材料生产组件，其中组件是基于三维计算机模型逐层生产的。在塑料加工领域，熔融沉积成型是迄今为止最常用的增材制造工艺。迄今为止，基于聚合物的熔融沉积模型的研究工作几乎完全关注具有柔性大分子链的传统聚合物的使用。对于高强度组件，高性能热塑性塑料，如聚醚醚酮或聚醚酰亚胺被特别使用，在这些聚合物的喷嘴退出后，加工过程中引入的取向会部分放松。与此相反，液晶聚合物（LCP）由于其特殊的分子结构，即使在松弛状态下也表现出一定的择优取向。在本研究计划的范围内，将对熔融沉积建模过程中LCP分子的取向行为进行实验和模拟研究，以便随后在打印样品中获得高各向异性的力学性能。在此过程中，将通过实验研究熔融沉积建模过程中的路径规划和工艺参数（例如打印温度和长丝速度）如何影响分子取向，从而影响随后的样品性能。基于CFD的数值流动模拟是用来模拟熔融沉积建模过程中的熔化和冷却行为。因此，这些研究为提前优化路径规划策略和工艺参数奠定了科学基础，从而可以制造出具有高抗拉强度的结构部件。

Additive manufacturing allows the production of components without a mold using various types of materials, whereby the components are produced layer by layer based on a three-dimensional computer model. In the field of plastics processing, fused deposition modeling is by far the most commonly used additive manufacturing process. Research work in the polymer-based fused depo-sition modeling has so far been concerned almost exclusively with the use of conventional poly-mers with flexible macromolecular chains. For high-strength components, high-performance ther-moplastics such as polyetheretherketones or polyetherimides are used in particular, whereby orien-tations introduced by the processing partially relax after nozzle exit for these polymers.In contrast to this, Liquid crystalline polymers (LCP) exhibit a certain preferred orientation even in the relaxed state due to their special molecular structure. Within the scope of this research proposal, the orientation behavior of LCP molecules in the fused deposition modeling process will be investi-gated experimentally and simulatively, in order to subsequently achieve high anisotropic mechani-cal properties in printed specimens. In doing so, it is to be investigated experimentally how both the path planning and the process parameters (e.g. printing temperature and filament speed) during fused deposition modeling influence the molecule orientations and thus the subsequent specimen properties. Numerical flow simulation by means of CFD is to be used to simulate both the melting and the cooling behavior in the fused deposition modeling process. These investigations thus form the scientific base for optimizing path planning strategies and process parameters in advance to the fused deposition modeling process in such a way that structural components exhibiting high tensile strength can be manufactured.