Development of Toughened Recycled Polyethylene Terephthalate and Micronized Rubber Composites for 3D Printing Applications: Compatibilization Strategies and Performance Assessment

Plastic pollution has become a pressing global crisis that threatens biodiversity and reduces the adaptability of the ecosystem to climate change. Additive manufacturing technologies hold promise in the context of distributed recycling and sustainability. The present work elaborates on developing low-cost, robust feedstocks with improved toughness based on postconsumer polyethylene terephthalate, rPET, and micronized scrap tire rubber powder (MRP) for additive manufacturing. The effects of a series of nonreactive (polystyrene-block-polybutadiene-block-polystyrene (SBS) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS)) and reactive compatibilizers (polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-g-maleic anhydride (SEBS-g-MA), poly(ethylene-co-glycidyl methacrylate) (EGMA), and poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (EMAGMA)) on the mechanical and rheological properties of rPET/MRP composites were investigated. rPET/MRP composites comprising compatibilizers with glycidyl moieties showed relatively higher impact strength and elongation at break. Rheological measurements revealed that incorporating MRP into rPET in the presence of compatibilizers remarkably increases melt viscosity, making the composite formulation suitable for extrusion processing. Differential scanning calorimetry results disclosed that reactive compatibilizers favorably reduce composite crystallinity compared to non-reactive ones, which are ascribed to the formation of long-chain branches. The potential of rPET/MRP filaments for fused deposition modeling was screened by using a low-budget desktop 3D printer. It is envisioned that the findings of this study will improve resource efficiency and the supply chain to achieve a waste-free economy and sustainability.