Shembekar Aditya Prakash, Yu Jason, Zhang Mingfu, Griffin Chris, Ray Dipa
School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, Robert Stevenson Road, Edinburgh EH9 3FB, UK.
Johns Manville, 10100 West Ute Avenue, Littleton, CO 80127, USA.
Polymers (Basel). 2025 Aug 7;17(15):2160. doi: 10.3390/polym17152160.
End-of-life (EoL) continuous glass fibre-reinforced polyamide 6 composites (cGF/PA6) are commonly recycled by shredding and milling, followed by injection moulding, often resulting in lower mechanical properties of second-generation products, primarily due to fibre length reduction. This study investigates the thermomechanical reprocessing of cGF/PA6 laminates via compression moulding, aiming to retain maximum mechanical performance by preserving the fibre length. Two types of 2/2 twill glass fibre-reinforced anionically polymerised polyamide 6 laminates (cGF/APA6), with either a reactive sizing agent (RS) or a non-reactive sizing agent (nRS), were reprocessed at two different temperatures, i.e., at 180 °C (between the glass transition temperature (T) and the melting temperature (T) of PA6) and 230 °C (above the melting temperature (T) of PA6). The influence of reprocessing on matrix crystallinity, thermomechanical properties, microstructure, and flexural performance was investigated. The results revealed that reprocessing at both temperatures led to an improvement in matrix crystallinity, retention of the desirable α-crystalline phases, and an elevated T (glass transition temperature) in both reprocessed laminates. Additionally, reprocessing at 180 °C maintained the flexural performance in both, whereas reprocessing at 230 °C led to nearly 20% improvement in flexural strength for the RS laminate. The microstructural analysis of the failed flexural specimens showed matrix-coated fibre surfaces, highlighting retained fibre-matrix adhesion. Overall, the results offer insights into the potential of compression moulding as a viable alternative for recycling cGF/APA6 laminates.
用于生命末期（EoL）的连续玻璃纤维增强聚酰胺6复合材料（cGF/PA6）通常通过粉碎和研磨进行回收，然后进行注塑成型，这往往会导致第二代产品的机械性能降低，主要原因是纤维长度缩短。本研究通过压缩成型研究了cGF/PA6层压板的热机械再加工，旨在通过保留纤维长度来保持最大机械性能。两种类型的2/2斜纹玻璃纤维增强阴离子聚合聚酰胺6层压板（cGF/APA6），分别使用反应性上浆剂（RS）或非反应性上浆剂（nRS），在两个不同温度下进行再加工，即180°C（介于PA6的玻璃化转变温度（T）和熔点温度（T）之间）和230°C（高于PA6的熔点温度（T））。研究了再加工对基体结晶度、热机械性能、微观结构和弯曲性能的影响。结果表明，在这两个温度下进行再加工均导致基体结晶度提高、所需α晶相得以保留，并且两种再加工层压板的玻璃化转变温度（T）升高。此外，在180°C下再加工使两者的弯曲性能均得以维持，而在230°C下再加工使RS层压板的弯曲强度提高了近20%。对失效弯曲试样的微观结构分析显示纤维表面有基体包覆，突出了纤维与基体之间保留的粘附力。总体而言，这些结果为压缩成型作为回收cGF/APA6层压板的可行替代方法的潜力提供了见解。
