Recycling of Discontinuous Long Fibre Thermoplastic Composites

由于其公认的性能、可定制性和制造优势，复合材料在越来越多的应用中继续取代金属。虽然连续纤维复合材料是用于替代航空航天应用中的金属部件的主要材料，但它们目前的使用通常限于大型壳状结构。因此，在航空航天工业中出现了以较小规模使用复合材料来代替形状复杂的金属部件的兴趣。介于传统连续纤维复合材料和短纤维注射塑料之间的是不连续长纤维（DLF）复合材料，这是一种块状模塑料类型的材料，由随机取向的预浸带碎片组成，可以压缩成型为复杂形状的部件。该工艺对于金属零件的替代是非常有吸引力的候选，因为它提供了生产具有复杂特征的净形部件的可能性。通过生产净形或近净形零件，材料浪费大大减少，同时实际上消除了对传统成型后操作（如切割、修边和/或钻孔）的需求。此外，最近的研究表明，DLF热塑性复合材料具有完全可回收的潜力。然而，这种技术的发展并不是微不足道的，主要是由于涉及DLF复合材料零件加工的挑战。拟议的研究计划的主要目标是开发一个强大的处理方案，有效地回收聚合物复合材料。材料系统将由热塑性预浸带组成，这种材料越来越多地用于航空航天应用。使用一个框架，包括处理和表征，将开发一种方法来评估的效果的关键处理相关的特性上的准静态和疲劳行为的两种类型的回收DLF复合材料。这项研究的结果将有助于确定在设计和制造回收DLF复合材料部件时要考虑的主要驱动因素。该计划将开发新的加工方法和过程控制技术，以进一步提高热塑性复合材料的生命周期和可持续性。

Composite materials continue to replace metal in a growing number of applications due to their recognized performance, tailorability, and manufacturing advantages. While continuous fibre composites are the primary materials employed to replace metallic components in aerospace applications, their current use is generally limited to large shell-like structures. There is thus an emerging interest in the aerospace industry to use composite materials at a smaller scale to replace complex-shaped metallic components. Lying between traditional continuous fibre composites and short-fibre injected plastics are Discontinuous Long Fibre (DLF) composites, a bulk moulding compound type of material comprised of randomly oriented chips of prepreg tape that can be compression moulded into complex-shaped parts. This process is a very attractive candidate for the replacement of metallic parts, as it offers the possibility to produce net-shaped components having complex features. By producing net or near-net shape parts, material waste is considerably reduced, while the need for traditional post-moulding operations such as cutting, trimming and/or drilling is practically eliminated. Moreover, recent studies have demonstrated that DLF thermoplastic composites have potential to be fully recyclable. However, the development of such a technology is not trivial, mainly due to the challenges involving the processing of DLF composite parts. The main objective of the proposed research program is to develop a robust processing scheme for efficient recycling of polymer composites. The material system will consist of thermoplastic prepreg tape, which is increasingly used in aerospace applications. Using a framework that includes processing and characterization, a methodology will be developed to evaluate the effect of key processing related characteristics on the quasi-static and fatigue behaviour of two types of recycled DLF composites. The findings of this study will help determine the main drivers to take into account during the design and manufacturing of recycled DLF composite parts. The proposed program will develop new processing methods and process control technologies to further increase the life cycle and sustainability of thermoplastic composites.