Recycling of Discontinuous Long Fibre Thermoplastic Composites

复合材料由于其公认的性能、可裁剪和制造优势，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在航空航天应用中取代金属部件的主要材料，但目前它们的使用通常仅限于大型壳状结构。因此，在航空航天工业中出现了一种新的兴趣，即以较小的规模使用复合材料来取代复杂形状的金属部件。介于传统的连续纤维复合材料和短纤维注射塑料之间的是非连续长纤维(DLF)复合材料，它是一种由随机取向的预浸带切片组成的大宗模塑复合材料类型，可以压缩成型成复杂的形状部件。该工艺是替代金属部件的一种非常有吸引力的候选工艺，因为它提供了生产具有复杂特征的网状部件的可能性。通过生产净或近净形状零件，材料浪费大大减少，同时几乎不再需要传统的模压后操作，如切割、修边和/或钻孔。此外，最近的研究表明，DLF热塑性复合材料具有完全可回收利用的潜力。然而，这种技术的发展并不是微不足道的，主要是因为涉及DLF复合材料部件加工的挑战。建议的研究计划的主要目标是开发一种稳健的加工方案，以有效地回收聚合物复合材料。材料系统将由热塑性预浸胶胶带组成，这种胶带越来越多地用于航空航天应用。利用一个包括加工和表征的框架，将开发一种方法来评估与加工相关的关键特性对两种类型回收DLF复合材料的准静态和疲劳行为的影响。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。拟议的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.