Developing multifunctional and environmental-friendly hot-pressed peanut meal protein adhesive based on peanut waste

Abstract

Hot-pressed peanut meal protein (HPMP) adhesives showed great potential as an alternative to formaldehyde-based adhesives because of their renewability and environmental-friendly, but their practical applications are severely limited by the poor bonding strength, water resistance and anti-mildew properties. Inspired by the spider leg structure, the functional graded peanut shell fiber (Ag/ZnO@APSF) loaded with metal nanoparticles was constructed through the biomineralization strategy as mineralized skeleton; Luteolin Epoxide (LE) as crosslinking agent. We had developed a green strategy for fabricating a novel HPMP adhesive with strong water resistance, high bonding strength, and strong mold resistance was prepared through a steel bars-concrete network structure using peanut waste, Ag/ZnO@APSF and LE. Compared with pure HPMP adhesive, the dry shear strength and wet shear strength of adhesive increased by 114% (2.29 MPa) and 257.9% (1.36 MPa), respectively. The residual rate increased by 43.8%, the moisture absorption rate and viscosity decreased by 48% and 45.4%, respectively. The adhesive had excellent flame retardancy with a reduction of 35.2% in peak heat release rate and 28.4% in total heat release rate, respectively. The antimildew time increased from 1 d to more than 45 d. In addition, the HPMP adhesive exhibited long-term adhesion behavior (pot life of 14 d), the pre-pressing bonding strength increased by 175.7% (1.02 MPa). This strategy had enhanced the added value of peanut waste and contributed to the development of multifunctional new plant protein adhesives.