Hongji Li,Rui Wang,Miao Zheng,Mingyun He,Xiaorong Liu,Kaili Wang,Youming Dong,Yanjun Li,Jianzhang Li
Soy protein-based adhesives present a promising alternative to petroleum-based adhesives in the wood industry. Nevertheless, their limitations, including insufficient water resistance, low bonding strength, and inadequate mold resistance, constrain their industrial applications. Plant fiber-reinforced composites find extensive applications across various sectors, including furniture, automotive, and aerospace. However, the smooth surfaces of the fibers adversely impact the reinforcement effect. Inspired by the multilayered microscale structure of peacock mantis shrimp chelipeds, this work presents an eco-friendly method to develop hierarchical functionalized kenaf fibers (KF) for reinforcing soybean meal (SM) adhesive. Specifically, ZnO was deposited onto the KF surface to impart micro-nano roughness, thereby enhancing their mechanical interlocking effect with the SM matrix. Bio-based lipoic acid (LA) and limonene (LIM) were employed to create a highly reactive layer on the fiber surface, facilitating the formation of multiple chemical crosslinking structures with the SM matrix. The synergistic mechanical and chemical effects between KF and SM endowed adhesive with improved performance. The wet shear strength of the three-layer plywood prepared with the synthetic adhesive was remarkably increased by 450 % to 1.21 MPa. Additionally, the combined anti-mold effects of ZnO, LA, LIM, and triglyceride amine (TGA) extend the adhesive's storage time to 7 days. This sustainable and eco-friendly design of multilayered bionically functionalized KF offers an efficient approach for the high-value utilization of agroforestry residues, presenting broad application prospects in SM-based adhesives.
Lignin has a UV-blocking ability because it contains phenolic and ketone functional groups. However, the lignin produced in the paper industry undergoes extreme polycondensation, resulting in an extremely dark color, which impedes its value-added application in the field of UV-blocking cosmetics. In this study, maleic acid (MA) was used as a green and recyclable reagent to pretreat an agricultural waste lignocellulosic biomass, Kenaf stalk. Lignin underwent a carboxyl esterification reaction with MA to produce light-colored dissolved lignin (DL), which was further prepared into lignin nanospheres and used in lignin-based sunscreens. The results showed that when adding 5 wt% DL-lignin nanospheres (DL-LNPs) to a sunscreen with an actual measured sun protection factor (SPF) of 7.05, the SPF of the lignin-based sunscreen increased to 63.82 far exceeding the commercially available SPF 50 sunscreens. The prepared lignin-based sunscreen had good biocompatibility when applied to human skin and did not stain the skin. The remaining neutral solid after pretreatment was made into Kenaf fibers by PFI milling for papermaking. The ring crush strength index of the paper increased from 2.81 N m/g to 3.14 N m/g when 15 wt% Kenaf fibers was added to the softwood pulp. When the additions Kenaf fibers was 5 wt%, the tensile index and tearing index of the paper increased from 8.57 N m/g and 4.68 mN m 2 /g to 9.22 N m/g and 5.48 mN m 2 /g, respectively. Therefore, this study provides a new way for the value-added utilization of Kenaf stalk lignocellulosic biomass. Graphical abstract