Fundamental investigation of potentially recyclable intrinsic polymer fiber-reinforced plastics for local component strengthening by 3D printing using fused filament fabrication FFF

对于许多应用来说，整洁塑料的结构性能是不够的。因此，为了改善这些性能，通常使用纤维来增强聚合物。然而，这通常也会导致更高的密度，并限制机械回收的潜力，因为增强效果取决于纤维长度，而在螺杆机中进行机械回收时，这些长度不可避免地会缩短。这就是微纤维复合材料(MFC)的用武之地。它们是根据M.Evstiev和S.Fakirov(Polmer 1992，33,877)的想法制造的，并结合了纤维形状的承载优势和塑料的低密度。在以往的工作中，聚合物纤维在注塑成型中的增强效果不能得到充分发挥，因为这种工艺会产生纤维在体积中的随机取向。本项目提案的基本思想是更好地利用熔融纤维制造(FFF)的MFC优势，以期实现平面3D轮廓结构。初步研究表明，使用MFC可以显著提高刚度和强度，并且可以在不损失机械性能的情况下容忍多次通过螺杆机，即潜在的机械可循环利用。在该项目中，将对FFF/MFC组合的潜力进行系统和弹性的研究。拟议项目的总体目标是通过将MFC和FFF联系起来，并深入了解工艺、形态和机械性能之间的关系，开辟一条获得高性能和可回收产品的途径，作为对传统不连续长纤维增强塑料的补充。具体地说，目标是：(1)具体开发塑料部件中定向不连续长纤维聚合物增强的各向异性特性，(2)以模拟和形态相关的方式调查和评估印刷参数对所得部件性能的影响，(3)调查相容剂对纤维形成和纤维-基质粘合的影响，以及(4)从部件设计和可回收性的角度评价材料/工艺组合的适宜性。

For many applications, the structural properties of neat plastics are insufficient. To improve these properties, polymers are therefore classically reinforced with fibers. However, these usually also result in a higher density and also limit the potential for mechanical recycling, since the reinforcing effect depends on the fiber length and these are inevitably shortened during mechanical recycling in screw machines. This is where microfibrillar composites (MFCs) come in. They are manufactured according to an idea by M. Evstatiev and S. Fakirov (Polymer 1992, 33, 877) and combine the load-bearing advantages of the fiber shape with the low density of plastics. In previous work, it became clear that the reinforcing effect of polymeric fibers in molded part production by injection molding cannot fully exploit since this process generates randomized orientation of the fibers in the volume.The fundamental idea of the present project proposal is to better exploit the advantages of MFC using Fused Filament Fabrication (FFF) with a view to planar 3D contoured structures. Preliminary investigations demonstrates that significant increases in stiffness and strength are possible with MFC and that a multiple pass through a screw machine can be tolerated without losses in the mechanical properties, i.e. mechanical recyclability is potentially available.In the project, the potentials of the FFF/MFC combination are to be systematically and resiliently researched. The overall goal of the proposed project is to open a pathway to high performance and recyclable products as a complement to conventional discontinuous long fiber reinforced plastics by linking MFC and FFF and developing a deep understanding of the relationships between process, morphology and mechanical properties. Specifically, the objectives are:(1) to specifically exploit the orthotropy properties of directional discontinuous long fiber polymer reinforcement in plastic components,(2) to investigate and evaluate the effect of the printing parameter on the resulting component properties in a simulation-based and morphology-related manner,(3) to investigate the influence of compatibilizers on fibril formation and fibril-matrix adhesion, and(4) to evaluate the suitability of the material/process combination in terms of component design and recyclability.