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

增材制造允许使用各种类型的材料在没有模具的情况下生产部件，由此基于三维计算机模型逐层生产部件。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，聚合物熔融沉积模型的研究工作几乎完全是使用具有柔性大分子链的常规聚合物。对于高强度部件，特别是使用高性能热塑性塑料，如聚醚醚酮或聚醚酰亚胺，这些聚合物在喷嘴出口后由加工引入的取向部分松弛。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。在本研究建议的范围内，LCP分子在熔融沉积成型过程中的取向行为将通过实验和模拟进行研究，以便随后在打印试样中实现高各向异性的机械性能。在这样做时，它是要实验研究如何在熔融沉积建模过程中的路径规划和工艺参数（例如打印温度和灯丝速度）的影响分子取向，从而随后的试样性能。通过CFD的数值流动模拟将用于模拟熔融沉积成型过程中的熔化和冷却行为。因此，这些研究形成了科学的基础，优化路径规划策略和工艺参数提前熔融沉积成型过程中，这样的方式，表现出高抗拉强度的结构部件可以制造。

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.