Effect of recycling on mechanical and physical properties of polycarbonate/acrylonitrile–butadiene–styrene/poly(methyl methacrylate) ( <scp>PC</scp> / <scp>ABS</scp> / <scp>PMMA)</scp> blends

Abstract

Abstract Plastics are widely used for their cost and versatility, but rising waste volumes demand effective recycling. In this context, it is important to understand the intrinsic degradation mechanisms of polymer blends commonly found in waste electrical and electronic equipment, particularly polycarbonate (PC) and acrylonitrile–butadiene–styrene (ABS) blends, which constitute a significant portion of collected computers. This study presents a laboratory‐scale model to analyze the thermomechanical degradation of virgin PC/ABS blends, with and without recycled poly(methyl methacrylate) (PMMA) as a low‐cost compatibilizer. Blends were prepared via counter‐rotating twin‐screw extrusion and injection molding, and then subjected to multiple recycling cycles to evaluate their recyclability and quantify the effects on mechanical, rheological, chemical and thermal properties of the optimal formulations identified through a mixture design desirability approach. Fourier transport infrared analysis revealed decreasing peak intensities, confirming chemical degradation of the polymer chains. TGA showed a progressive reduction in onset degradation temperature, with the AM blend (83.1 wt% PC, 16.9 wt% ABS) exhibiting higher thermal stability than the M10 blend (73.75 wt% PC, 23.75 wt% ABS, 2.5 wt% PMMA). DSC results further indicated a decline in glass transition temperature, consistent with reduced molecular weight after successive recycling cycles. An increase in the melt flow index was also observed, correlating with the deterioration of mechanical properties including tensile strength, elongation at break, flexural modulus and Charpy impact resistance. This degradation was more pronounced in the M10 blend, underscoring its greater sensitivity to thermal and mechanical stresses during repeated reprocessing. © 2026 The Author(s). Polymer International published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry.