Injection moulding compounders: Integrated processing route for enhanced thermoplastic composite performance?

The growing demand for sustainable manufacturing necessitates innovative strategies to upcycle recycled and regenerated polymers into high-performance, lightweight components. The objective of this study is to evaluate the feasibility and performance of the Injection Moulding Compounder (IMC) as an integrated one-step processing route for manufacturing lightweight components from recycled polymer systems. Numerical simulations using Ansys POLYFLOW® were employed to analyse the effects of process design on pressure build-up, shear stresses, and residence time within the IMC system, and the modelling outcomes were validated against experimental measurements. Post-consumer recycled polypropylene (PP) blended with shredded post-industrial glass fibre-reinforced PP served as the material feedstock. Comprehensive thermal, rheological, and mechanical characterization of the one-step IMC-processed components revealed nominal differences with conventional-processed components, which compounded in a twin-screw extruder and then injection moulded. Regarding mechanical properties, less than 10% differences were observed in the tensile and flexural properties, showing the similarity of the components produced by IMC and conventional method. The novelty of this work lies in the combined numerical and experimental assessment of the developed IMC for the direct processing of recycled, fibre-reinforced thermoplastics. The results demonstrate that the proposed single-step process can achieve mechanical performance comparable to conventional processing routes while reducing material handling and processing complexity. These findings highlight the IMC's capability to couple material performance enhancement with environmental benefits, highlighting its role as a scalable pathway for circular economy implementation and the advancement of resource- and energy-efficient polymer processing technologies.