Alkali enhanced common reed properties for bio - composite applications

Abstract

This thesis investigates the effect of alkali treatment using sodium hydroxide on the structuraland chemical properties of common reed for application in bio-composites. The aim was to evaluate how NaOH treatment influences reed fiber performance in composite materials and to assess compatibility with three thermoplastic polymers: PP, PLA, and HDPE. The study employed a fixed NaOH concentration (4.5%) and treatment duration (five hours) to process reed fibers, which were subsequently incorporated at 20 wt% into the polymer matrices. Composite formulations were processed via micro-compounding and injection molding. Characterization was conducted using FTIR to identify chemical changes, optical microscopy for structural analysis, and Melt Flow Index testing to evaluate flow behavior. FTIR results confirmed the successful removal of hemicellulose and lignin, as evidenced by the disappearance of the C=O peak at 1730 cm⁻¹ and sharpening of cellulose-associated peaks, indicating increased crystallinity. Microscopy revealed enhanced fiber dispersion, reduced interfacial gaps, and improved matrix adhesion in treated composites. These effects were most prominent in PP and PLA composites. However, MFI testing yielded inconsistent results due to equipment limitations and moisture-related issues, with only HDPE-based composites providing valid flow data. The findings affirm that NaOH treatment improves reed fiber integration and structural characteristics in bio-composites but highlight challenges in optimizing treatment conditions and processing parameters. Future work should explore varied treatment settings and incorporate mechanical testing to quantify composite performance better.