ABSTRACT Cellulose papers are sustainable alternatives to plastics but are often limited by poor water resistance and barrier properties. This study introduces a method to overcome these limitations by integrating softwood kraft lignin as a functional filler. Micronized lignin particles (4 µm) were produced via wet grinding and dispersed into a paper matrix at loadings up to 40%, followed by high‐temperature pressing (160°C) to soften the lignin. This process created a composite with exceptional interfacial bonding between the softening lignin and cellulose fibers, yielding outstanding mechanical properties: a tensile strength of 82 MPa, a folding endurance of 891 cycles, and a density of 1 g/cm 3 . The barrier properties were also significantly enhanced, with water vapor and oxygen transmission rates reduced to 287 g/m 2 ·d and 114 cm 3 /m 2 ·d·0.1 MPa, respectively, representing decreases of 67% and 73% compared to conventional paperboard. This work establishes a viable paradigm for creating high‐performance, fully biodegradable lignin‐cellulose composites that bridge the functionality gap between paper and plastic, demonstrating immediate potential for sustainable packaging and covering applications.
Huang et al. (2026) studied this question.