Using a Novel Expansion-Die in the Field of Injection Molding for Generating Anisotropic Thermal Conductivity

在聚合物基复合材料中使用导热填料，可以针对各自的应用领域有意地调整导热性。例如，LED，光伏系统和微处理器需要材料表现出高度的各向异性导热性和良好的电绝缘性。为了满足这些要求，通常需要高填料含量。不幸的是，这些高填料含量对各自材料的可加工性有很大的负面影响。避免这一问题的一种方法是在热塑性塑料加工过程中故意的填料方向。尽管填料含量相对较低，但另一种允许良好导热性的方法是使用液晶聚合物（LCP）代替传统聚合物。由于其化学结构，LCP表现出特别适合作为基体材料，通过热塑性加工技术产生高导热性。申请人打算使用注射成型领域的一种新型膨胀模具来生产具有高度各向异性导热性和优化填料含量的板材。在本研究计划的范围内，将利用一种新的扩展模具来定制功能填料的对齐以及LCP矩阵。为此，在IKT之前开发的膨胀注射成型工艺应使用。这一过程使模具在垂直于流动方向的方向上有一个额外的膨胀行程。填料的方向以及因此而产生的薄板的导热性应根据膨胀行程、膨胀速度、模具温度和注射速度进行具体调整。通过改变加工条件，这两个组件的取向行为将被研究与处理剪切和伸长变形过程有关。

Using thermally conductive fillers in polymer-based composites allows for the deliberate adjustment of thermal conductivity for the respective area of application. For instance, LED, photovoltaic sys-tems and microprocessors require materials exhibiting a highly anisotropic thermal conductivity combined with a good electrical insulation. In order to meet these requirements high filler contents are usually necessary. Unfortunately, these high filler contents have a highly negative impact on the processability of the respective materials. One way to avoid this issue is the deliberate orientation of the fillers during thermoplastic processing. Another way to allow for good thermal conductivity de-spite a relatively low filler content is the use of Liquid Crystal Polymers (LCP) instead of conven-tional polymers. Due to their chemical structure, LCP show a particularly suitable behavior as a ma-trix material for generating a high thermal conductivity by means of thermoplastic processing tech-niques. The applicant intends to use a novel expansion die in the field of injection molding to pro-duce sheets with highly anisotropic thermal conductivity and an optimized filler content.Within the scope of this research proposal a novel expansion die will be utilized in order to tailor the alignment of the functional fillers as well as of the LCP matrix. For this purpose, the expansion in-jection molding process shall be used which was previously developed at the IKT. This process al-lows an additional expansion stroke of the mold perpendicular to the flow direction. The filler orien-tation and hence the thermal conductivity of the sheets is to be specifically adjusted as a function of the expansion stroke, expansion speed, mold temperature and injection speed. By varying the pro-cessing conditions, the orientation behavior of both components will be investigated with regards to the proceeding shear and elongational deformation processes.