Green manufacturing of bamboo self-bonding composites with superior mechanical and electromagnetic interference shielding performance

Abstract

To tackle formaldehyde emissions from building materials and increasing electromagnetic radiation pollution, the development of lightweight, efficient, and eco-friendly electromagnetic interference (EMI) shielding materials has gained growing momentum. Herein, high-consistency mechano-enzymatic (HCME) pretreatment followed by hot pressing was employed to transform bamboo processing residues into bamboo self-bonding composites (BSBC). The effects of enzyme dosages and pretreatment durations on the microstructure and materials properties of BSBC were systematically investigated. The results revealed that higher enzyme dosage, longer pretreatment duration, or a combination thereof were favorable for the formation of abundant sub-fibrous branches and a more compact physical entanglement, thereby leading to strengthened BSBC. With an enzyme dosage of 0.035 g/g biomass and a 4-hour HCME duration, the BSBC achieved excellent flexural strength (37.1 MPa) and internal bonding strength (2.42 MPa), increasing by 61.1% and 66.9%, respectively, compared to those without HCME pretreatment. Additionally, the BSBC exhibited a low thickness swelling rate (5.6%) and low porosity (3.08%), meeting the standard requirements for general-purpose high-density fiberboards. The incorporation of graphene further endowed the BSBC with effective EMI shielding performance, achieving an EMI shielding efficiency of 31.94 dB. The adhesive-free, environmentally friendly, and green manufacturing features, along with the superior EMI shielding performance and mechanical performance, make it a promising sustainable EMI shielding material to be potentially used in secure conference rooms and data centers.