Study of Aramid Fiber/Polychloroprene Recycling Process by Thermal Degradation

ABSTRACT Aramid fiber is an important polymer applied as reinforcement in high-performance composites, which, due its exceptional properties, becomes an excellent impact absorption material. It has been broadly utilized in aeronautic industry and ballistic protection. In aircrafts, it is mainly used in secondary structures, such as fairings, floor panels, and bullet proof structures in helicopters, whereas, in ballistic protection industry, it is applied in automotive armor and bullet proof vest. Under environmental perspective, it is worrying the development and application of composites, which generate proportional discards of these materials, whether originated from manufacturing process, spare parts or end of life cycle. High-performance composite materials like those using aramid fiber are generally difficult to recycle due to their properties and the difficulty for the separation of the components, making their recycling economically unviable. From the characteristics of composite materials and environmental viewpoint, this paper presents a new aramid fiber recycling process. The main objective of this research was to study different recycling methods in aramid fibers/Neoprene® composites. To promote the Neoprene® degradation, it was used a pyrolysis oven with controlled atmosphere and CO2 injection. For the degraded separation, it was designed a mechanical washing machine in which the most degraded separation occurred. To complete the materials separation, it was employed a manual cleaning process, and, at least to prove the efficacy of the process, it was applied a tensile test in the yarns.

摘要：芳纶纤维（Aramid fiber）是一类重要的聚合物，可用作高性能复合材料（high-performance composites）的增强材料，凭借其优异性能成为优质吸能材料，目前已广泛应用于航空航天工业与弹道防护领域。在航空领域，其主要用于飞机次要结构，如整流罩、地板面板及直升机防弹结构；在弹道防护工业中，则被应用于车用装甲与防弹背心。从环境视角来看，复合材料开发与应用所产生的对应废弃物问题令人担忧，此类废弃物既可能源自制造流程、备件环节，也可能产生于产品生命周期末端。以芳纶纤维为基材的高性能复合材料，由于自身特性及组分分离难度大，通常难以回收，导致其回收利用在经济上不可行。基于复合材料特性与环境考量，本文提出了一种新型芳纶纤维回收工艺。本研究的核心目标是探究芳纶纤维/氯丁橡胶（Neoprene®）复合材料的多种回收方法：为促进氯丁橡胶降解，采用了带有可控气氛并注入二氧化碳的热解炉（pyrolysis oven）；为实现降解产物的分离，设计了机械洗涤装置，可完成高效的降解产物分离；为完成最终的材料分离，辅以人工清洗工序；最后，通过对回收得到的纤维纱线开展拉伸试验（tensile test），验证了该回收工艺的有效性。