Pea Pod Valorization: A Green Processing Route to Obtain Cellulosic Reinforcements for Compression Molded Polylactic...

Area of Science:

• Materials Science
• Sustainable Chemistry
• Biocomposites

Background:

• Agroindustrial residues offer a sustainable source for novel material development.
• Cellulosic materials can serve as reinforcements in biocomposites.
• Pea pods are an abundant agroindustrial residue with potential for valorization.

Purpose of the Study:

• To isolate and characterize cellulosic materials from treated pea pods.
• To develop and evaluate biocomposites using these cellulosic reinforcements and a polylactic acid matrix.
• To investigate the effect of different treatment concentrations and percentages of reinforcement on composite properties.

Main Methods:

• Pea pods were treated with oxalic acid (OA) and potassium hydroxide (KOH) solutions.
• Cellulosic materials were compounded with polylactic acid (PLA) and polyvinyl alcohol (PVA) via extrusion.
• Compression molding was used to fabricate composite samples.
• Characterization included Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC), and mechanical testing (flexural, thermo-mechanical).

Main Results:

• Cellulosic reinforcements from 0.75 M OA and 0.5 M OA + KOH treatments exhibited high crystallinity (91-92%).
• Composites with 20 wt.% reinforcement generally showed lower thermal expansion and higher water absorption than 10 wt.%.
• Composites with 10 wt.% OA-treated reinforcements showed 17% higher flexural modulus and 3% higher strength than PLA.
• Composites with 20 wt.% OA + KOH-treated reinforcements displayed a 35% increase in flexural modulus and a 25% increase in strength compared to PLA.

Conclusions:

• Agroresidues, like pea pods, can be effectively valorized into high-performance cellulosic reinforcements.
• Low-concentration organic acid treatments are sufficient for producing effective reinforcements.
• These treated cellulosic materials can significantly tune the mechanical, thermal, and water absorption properties of biodegradable composites.
• This approach offers a sustainable pathway for developing advanced biocomposites.