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Mildly delignified wood showed a well-preserved wood cell wall framework, and its derived compressed materials demonstrate excellent mechanical properties and advanced functional material potential. Here, we proposed a simple yet effective approach for making strong, tough, and fire-retardant wooden laminate by a three-step process of mild delignification, infiltrating potassium nonafluoro-1-butanesulfonate (PFBS), and hot-pressing to densify the material. PFBS can be infiltrated into the micro/nano-structures of the mildly delignified wood to achieve a good flame-resistant protective barrier. Flame retardant tests showed that this strong, tough, and fire-retardant wooden laminate has a superior flame-retardant performance to natural wood. Additionally, the wooden laminate also exhibits a simultaneously enhanced tensile strength (175.6 MPa vs. 89.9 MPa for natural wood) and toughness (22.9 MJ m−3 vs. 10.9 MJ m−3 for natural wood). Given these attributes, the resulting wooden laminates are identified as promising candidates for high-performance structural applications, fulfilling stringent requirements for both mechanical resilience and flame-retardant efficacy. [ABSTRACT FROM AUTHOR]

Superior strong and tough structural materials are highly desirable in engineering applications. However, it remains a big challenge to combine these two mutually exclusive mechanical properties into one body. In the work, an ultrastrong and tough cellulosic material was fabricated by a two-step process of delignification and water molecule-induced hydrogen bonding under compression. The strong and tough cellulosic material showed enhanced tensile strength (352 MPa vs. 56 MPa for natural wood) and toughness (4.1 MJ m−3 vs. 0.42 MJ m−3 for natural wood). The mechanical behaviors of ultrastrong and tough bulk material in a tensile state were simulated by finite element analysis (FEA) using mechanical parameters measured in the experiment. FEA results showed that the tensile strength and toughness gradually simultaneously improved with the increase in moisture content, demonstrating that water molecules played an active role in fabricating strong and tough materials, by plasticizing and forming hydrogen bonding among cellulose nanofibrils. [ABSTRACT FROM AUTHOR]

Wooden building materials have advantages in terms of biodegradability, non-toxicity, pollution-free and recycling. Currently, applications of natural wood are extremely limited because of low density, low strength and toughness. Therefore, we reported an effective modification strategy with nano-scale cellulose nanofibrils design to prepare a synergistically enhanced cellulosic material. Via three steps: i) the secondary alcohol hydroxyl groups in C 2 , C 3 position were cut; ii) oxidize the hydroxyl group at C 2 , C 3 position to achieve dialdehyde cellulose; and iii) oxidized again to obtain dicarboxylic cellulose. Subsequently, thanks to the regulation of the average moisture content, the moisture content in the wood surface and subsurface increased in a short time. The wood softening layer contributes to the hotpressing treatment of the wood. The mechanical properties and dimensionality have been greatly improved. The obtained delignified oxidated hot-pressed wood with 0.55 mmol/g carboxyl group content demonstrates excellent strength of 328.8 ± 7.43 MPa and Young's modulus of 8.1 ± 0.14 GPa, which is twice than that of natural wood. Delignified oxidated hot-pressed wood also shows exceptional toughness of 8.3 ± 0.28 MJ/m3. Other than that, the shore hardness indicates 0.55 mmol/g carboxylic group, which could increase the hardness at the wood surface hardness to 72.5 ± 4.29°. [ABSTRACT FROM AUTHOR]

Holocellulose nanofibrils (HCNFs) are nanoscale objects extracted from biomass resources and have attracted attention as sustainable building blocks for nanomaterials. In this study, we report a top-down approach for extracting HCNFs from manau rattan that involves pulping, bleaching and TEMPO oxidation. The extracted HCNFs showed a uniform width of around 18.5 nm and a length of a few micrometers, high crystallinity (66.5 %), and good thermal stability (302 °C). The extracted HCNFs were used to fabricate HCNF film via vacuum filtration and drying (air drying and solvent exchange drying). Surprisingly, the HCNF film fabricated by solvent exchange drying (HCNF-film SD) simultaneously presented a high total transmittance (93.7 %) and high haze (62.2 %), and its total transmittance was even higher than that of glass. The resulting HCNF-film SD displayed a high tensile strength (84.8 MPa), Young's modulus (3.7 GPa), and toughness (1.4 MJ m−3), making it a high-performance and eco-friendly film for applications in precision optoelectronics and aerospace materials. Manau rattan HCNFs were extracted by pulping, bleaching and TEMPO oxidation, and HCNF film SD with simultaneously high transmittance (93.7 %) and high haze (62.2 %) was fabricated via a simple vacuum filtration and solvent exchange, followed by ambient drying method. [Display omitted] • Manau rattan HCNFs were extracted using pulping, bleaching, and TEMPO oxidation. • HCNF-filmSD was prepared via vacuum filtration and solvent exchange, followed by ambient drying. • HCNF-filmSD simultaneously showed high transmittance (93.7 %) and haze (62.2 %). [ABSTRACT FROM AUTHOR]

Novel ultrastrong and tough natural cellulosic fiber bundles (RFs) extracted from vascular tissues of manau rattan stems were obtained and the RFs will play a promising role in the field of nano-advanced functional materials. [Display omitted] • Ultrastrong and tough natural cellulosic fiber bundles (RF) were prepared from vascular tissues of manau rattan stems. • RF S showed higher crystallinity and better thermal stability than RF M and RF L. • Tensile strength and toughness of the RF improved simultaneously as diameter decreased. Natural fibers are an ideal choice for fabricating advanced functional materials. In this study, novel ultrastrong and tough natural cellulosic fiber bundles (RFs) extracted from vascular tissues of manau rattan stems were obtained. The physical, mechanical, chemical, thermal, crystallographic, and morphological characteristics of RFs with different diameters were analyzed. The chemical composition analysis showed that more cellulose and less lignin existed in thinner RFs. Scanning electron microscopic images revealed that manau rattan was mainly composed of vascular bundles, consisting of xylem, parenchyma, and run-through thicker tracheids. X-ray diffraction analysis indicated the RF S had higher crystallinity (51.7 %) than RF M (49.7 %) and RF L (47.7 %). The rattan fiber bundles showed simultaneously enhanced tensile strength (170.2 for RF S vs. 65.6 MPa for RF L) and toughness (31.6 for RF S vs. 16.7 MJ/m3 for RF L) as diameter decreased. Tensile strength and toughness were 482.6 MPa and 79.9 MJ/m3 when RF diameter decreased to 0.15 mm. These findings suggested that these RFs will play a promising role in the field of nano-advanced functional materials. [ABSTRACT FROM AUTHOR]