Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microfilled anhydride-modified crude lignin blend biodegradable...

Area of Science:

• Materials Science
• Polymer Science
• Biocomposites

Background:

• Coir fibers, an agricultural byproduct, yield crude lignin suitable for sustainable material applications.
• Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polymer with potential for eco-friendly applications.
• Improving the compatibility of natural fillers with biopolymer matrices is crucial for developing advanced composites.

Purpose of the Study:

• To investigate the use of chemically modified lignin as a filler in PHBV biodegradable blends.
• To enhance the physical, mechanical, and thermal properties of PHBV composites.
• To evaluate the effect of lignin modification on filler-matrix miscibility and composite performance.

Main Methods:

• Lignin extracted from coir fibers was chemically modified using acetic and propionic anhydrides.
• Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA) were used for characterization.
• Blends were prepared via melt compounding and compression molding with varying percentages (1-7 wt%) of modified lignin.

Main Results:

• Modified lignins improved the physical, mechanical, and thermal properties of PHBV blends, with optimal performance at 5 wt% modified lignin.
• Propionylated lignin-based blends showed superior performance compared to acetylated and raw lignin blends due to enhanced filler-matrix miscibility.
• Lignin agglomeration at 7 wt% led to reduced performance, confirmed by morphology and tensile tests.

Conclusions:

• Chemically modified lignin, particularly propionylated lignin, serves as an effective and sustainable filler for PHBV biopolymer composites.
• The enhanced interfacial bonding and improved miscibility contribute to superior composite properties.
• These findings support the use of modified lignins in eco-friendly biopolymer composites for packaging applications.