Strong and antistatic biomass adhesive for wood-based composites with electrostatic discharge protection function

Abstract

Soybean protein adhesive, as an aldehyde-free biomass adhesive, has gained significant attention as an environmentally friendly material in recent years. It not only aligns with the objectives of the double carbon strategy but also contributes to the environmental protection strategy of reducing carbon emissions. And the functional modification of soybean protein adhesive and its wood composite hold great importance in expanding its application domains and meeting specialized requirements. This research focused on developing a robust, antistatic adhesive derived from soy protein as an alternative to formaldehyde-based resins, which represents a critical path in the advancement of wood-based composites that are free from formaldehyde and possess functional properties. However, ensuring the bonding strength of soy protein adhesive while developing antistatic adhesives and their wood-based composite materials is of great research value and challenge. Inspired by the organic-inorganic hybrid structure, this study aimed to prepare a strong and durable soy protein adhesive with excellent mechanical strength and multifunctionality by using a self-synthesized crosslinking agent called AP and the loaded two-dimensional MXene, which was stabilized in a dispersion of nanocellulose (CNC). The dry and wet shear strength of the resulting adhesive increased by 103.8 % and 113.8 % to 2.21 MPa and 1.24 MPa, indicating the stable crosslinking structure formed in adhesive system by the covalent bond between self-synthesized crosslinking agent AP and the carboxyl groups on proteins, as well as the hydrogen bond interactions between C-M and the proteins. Furthermore, the adhesive exhibited significant antistatic and self-extinguishing properties, with the particleboard modified by adhesive SPI/C-M/AP having a resistivity of 9.212 × 1011 Ω cm. The resistivity decreased with increasing MXene content, providing potential applications for places such as school computer rooms and factory electronic equipment rooms. This breakthrough in multifunctional biomass-based adhesives and composite materials enriches the preparation of new types of biomaterials with antistatic and flame retardant properties.