Fabrication and performance evaluation of recycled polypropylene based composite floor tiles incorporating biodegradable additives

This study develops recycled polypropylene (rPP)-based interlocking composite floor tiles reinforced with fly ash, corn starch, and sodium silicate to investigate the influence of hybrid fillers on their overall performance. The composites are fabricated through an injection molding technique using a custom-designed die with varying compositions of rPP (60–80 wt%), fly ash (10–20 wt%), corn starch (5–15 wt%), and sodium silicate (2–6 wt%). The fabricated samples are evaluated in terms of different mechanical, physical, and chemical properties, followed by morphological and structural characterization. Mechanical properties improve at optimized compositions and tend to decline at excessive reinforcements loading due to agglomeration and weak interfacial bonding. The optimal composite obtained from response surface methodology analysis exhibits tensile strength of approximately 34 MPa, flexural strength of 37.9 MPa, compressive strength of 40.76 MPa, impact energy of 27.65 J, and hardness of 59.32 BHN, along with low water absorption (0.758%) and chemical degradation (0.706%) that is identical to selected fabricated composite sample S7 determined by multi criteria ranking techniques in this research. Furthermore, microstructural analysis confirms uniform dispersion of fillers and enhanced interfacial adhesion within the matrix. Statistical modeling demonstrated high predictive accuracy (R² > 0.98) with low error margins (<3%), validating the robustness of the developed models. The originality of this work stems from the use of unexplored additives (corn starch and sodium silicate), a custom-designed die, and a multi-objective optimization framework involving 21 composite samples along with multiple characterization. Overall, this study implies an environmentally sustainable and technically viable approach for transforming plastic waste into high-value construction alternatives.