# Performance enhancement of wood composites using cellulose-reinforced cornstarch–tannin adhesives derived from electrical-assisted extraction

## TL;DR

This paper explores using electrical-assisted extraction to improve wood composites by creating formaldehyde-free adhesives from almond shell cellulose, resulting in stronger and more moisture-resistant particleboards.

## Contribution

The study introduces high-voltage electrical discharges as an effective method to extract cellulose from almond shells, enhancing adhesive performance in wood composites.

## Key findings

- HVED-assisted extraction improved cellulose crystallinity and thermal stability without altering its structure.
- Particleboards with HAC-CM adhesives exceeded EN 312 standards for mechanical properties.
- Water absorption and thickness swelling were significantly reduced in the treated composites.

## Abstract

This study investigates the impact of electrical-assisted extraction techniques on cellulose derived from almond shells and its performance in formaldehyde-free cornstarch–mimosa tannin (CM) adhesives. Cellulose was extracted using three methods: conventional alkali treatment (AT), alkali treatment assisted by pulsed electric fields (PEF), and alkali treatment assisted by high-voltage electrical discharges (HVED). Comprehensive analyses, including FTIR, XRD, TGA/DTG, DSC, and SEM, were conducted to evaluate the chemical structure, crystallinity, thermal stability, and morphology of the extracted celluloses. The results revealed that while cellulose yield varied slightly among treatments, electrical-assisted extraction significantly enhanced delignification and fibrillation without altering the cellulose I crystalline structure. Both PEF- and HVED-treated celluloses exhibited improved crystallinity (≈59%) and thermal stability (Tonset ≈ 303 °C), indicating superior structural integrity. Incorporation of these celluloses into CM adhesives increased viscosity, solid content, and shear strength, with optimal performance at 6 wt% cellulose loading. Particleboards bonded with HAC-CM adhesives showed the highest mechanical properties (IB = 0.79 MPa, MOR = 32.27 MPa, MOE = 3125 MPa), exceeding EN 312 (P4) standard requirements. Water absorption and thickness swelling were markedly reduced, confirming enhanced moisture resistance. Overall, HVED-assisted extraction produced cellulose with superior reinforcing capability, demonstrating a sustainable and high-performance pathway for developing formaldehyde-free wood adhesives from agricultural residues.

High-voltage electrical extraction transforms almond shell waste into reinforcing cellulose for starch–tannin adhesives. The resulting formaldehyde-free particleboards exhibit enhanced mechanical properties, meeting EN 312 standards.