Empowering Polyamide/Glass Fiber Composite Upcycling with Energy Sobriety Formulations via Reactive Extrusion

In this work, performing materials from chemical and mechanical recycling of PA/glass fiber (GF) composites using the reactive extrusion process were developed. Through the reduction of the viscosity of the PA by chemical modification using amino-terminated polyethers Jeffamine T403 and dimethyl terephthalate (DMT), the breakage of glass fibers was reduced. The decrease in melt viscosity, due to chain scission of polyamide-6 (PA6) or the formation of new branched structures within the polymer matrix, led to a significant improvement in processability. Although T403, when added alone, exerted a slight negative effect on mechanical properties, especially in terms of impact strength, the concomitant addition of DMT led to an improvement. This improvement in mechanical properties was attributed to the presence of longer GFs resulting from the lower viscosity of the medium and reduced shear damage, in addition to the formation of new structures that improve the mechanical properties of such composites. Furthermore, the study investigated the influence of two extrusion cycles on the composites’ mechanical properties and found that although it is ultimately decreased, the ultimate strength of T403 and DMT-based composites remained superior to that of PA6/GF alone. This suggests that the addition of Jeffamine T403 and DMT not only improves the initial properties of the composites but also enhances their recyclability. This study showed that through reactive extrusion and small quantities of modifying agents, the recycling process not only becomes less energy-consuming but also reduces the breakage of GFs and creates in situ branched structures that enhance the mechanical properties of PA with or without the presence of GFs.