A strong, hydrostable lignocellulose-based film based on dual cross-linking networks

Abstract

Green and sustainable biomass materials based on wood processing residues show considerable application potential as substitutes to petroleum-based plastics. However, due to the chemical and structural characteristics of cellulose fibers resulting in their natural hydrophilicity, it is difficult for a single cross-linking network to impart multiple excellent properties to bio-based materials. Here, with wood lignification enhancement inspiration, a high-performance bio-based plastics based on 2,2,6,6-tetramethylpiperidine-1-oxy-oxidized lignocellulose (TOLC) is successfully fabricated by a dual-crosslinking strategy of sodium lignosulfonate (LS) and epichlorohydrin (ECH) modification, and their characterizations were done in terms of SEM, FTIR, XPS, XRD, TG, contact angle and tensile properties. The physical sacrificial bonding between TOLC and LS, in conjunction with the covalent cross-linking network among the TOLC-LS matrix and ECH, contributed to the exceptional tensile strength (383.43 ± 1.57 MPa) and elastic modulus (15.20 ± 0.66 GPa) of the prepared TOLC-LS/ECH film. Furthermore, the maximum weight loss peak of TOLC-LS/ECH III film is observed at 348 °C, higher than TOLC film, which shows exceptional thermal stability. After immersing in water for 24 h, the water absorption rate of TOLC-LS/ECH III film is only 59.72 % of TOLC film, exhibiting increased water resistance. Remarkably, the resulted bio-mass plastics show superior biodegradability with a weight loss of 33.67 % after 30 days in outdoor conditions, while the tensile strength remained 81 % of the original after 6 months in appropriate indoor environments, showing excellent mechanical stability. Compared with most sustainable bio-based plastics, the obtained film shows combination of low production cost, high mechanical properties, and glorious thermal stability, which can effectively expand its application potential in mulch, daily packaging, and so on. This strategy will pave the way for developing sustainable bio-based plastics with low cost, high-performance, and outstanding processing.