Abstract

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This study investigates the effects of nanoclay (halloysite) on the dynamic mechanical behaviour of recycled polypropylene (rPP) composites reinforced with maize cob powder (MCP). The influence of filler loading (10–40 wt%), particle size (100–500 µm), 2 % NaOH surface treatment, and nanoclay content (2–8 wt%) on storage modulus (E′), loss modulus (E″), damping factor (tan δ), and glass transition temperature (Tg) were analyzed using a Netzsch DMA 242 dynamic mechanical analyzer. Results revealed that increasing MCP loading and decreasing particle size enhanced the stiffness and thermal stability of the composites. The addition of nanoclay further improved modulus and Tg by restricting polymer chain mobility. NaOH treatment enhanced interfacial bonding, leading to improved stiffness and damping behaviour. The highest Tg (122.6 °C) was recorded for 100 µm fillers at 40 % loading and 8 % nanoclay, demonstrating the synergistic reinforcement effect of MCP and nanoclay in rPP matrices. The improved viscoelastic properties suggest the suitability of rPP/MCP/nanoclay composites for applications requiring enhanced stiffness, thermal resistance, and vibration damping.

Keywords: Recycled Polypropylene (rPP), Maize Cob Powder (MCP), Halloysite Nanoclay (NC), Sodium Hydroxide (NaOH) Treatment, Dynamic Mechanical Properties