Residual-lignin-endowed molded pulp lunchbox with a sustained wet support strength

Abstract

A significant challenge in the design of pulp lunchboxes (PLBs) is the structural collapse driven by moisture. Inspired by the lignin in wood bonding activation, a simple and novel strategy is proposed in this study to sustain the wet support strength of PLB. Pulp with residual lignin (RL) is prepared from bamboo by bath treatment with HNO3 and H2O2, and the resulting PLB (RL-PLB) is obtained from the pulp by a mature molding process. Residual lignin with thermoplastic properties acts as a filler, binder, and hydrophobic agent, endowing the RL-PLB with wet-stability adhesion. Consequently, the RL-PLB exhibits a high mechanical strength of 44 MPa, stiffness of 12.9 mN m sustained wet support strength for over 30 d, and excellent wet stability. The RL-pulp used for manufacturing RL-PLB exhibits a high biomass-utilization efficiency with a yield of 75 %. RL-PLB is a biodegradable and eco-friendly substitute for non-biodegradable plastics.