Environment-friendly, high-performance cellulose nanofiber-vanillin epoxy nanocomposite with excellent mechanical, thermal insulation and UV shielding properties.

With the increased demand for biobased epoxy thermosets as an alternative to petroleum-based materials in various fields, developing environment-friendly and high-performance natural fiber-biobased epoxy nanocomposites is crucial for industrial applications. Herein, an environment-friendly nanocomposite is reported by introducing cellulose nanofiber (CNF) in situ interaction with lignin-derived vanillin epoxy (VE) monomer and 4, 4´-diaminodiphenyl methane (DDM) hardener that serves as a multifunctional platform. The CNF-VE nanocomposite is fabricated by simply dispersing the CNF suspension to the VE and DDM hardener solution through the in-situ reaction, and its mechanical properties and thermal insulation behavior, wettability, chemical resistance, and optical properties are evaluated with the CNF weight percent variation. The well-dispersed CNF-VE nanocomposite exhibited high tensile strength (∼127.78 ± 3.99 MPa) and strain-at-break (∼16.49 ± 0.61 %), haziness (∼50 %) and UV-shielding properties. The in situ loading of CNF forms covalent crosslinking with the VE and favors improving the mechanical properties along with the homogeneous dispersion of CNF. The CNF-VE nanocomposite also shows lower thermal conductivity (0.26 Wm-1K-1) than glass. The environment-friendly and high-performance nanocomposite provides multiple platforms and can be used for building materials.

Biobased, cellulose long filament-reinforced vanillin-derived epoxy composite for high-performance and flame-retardant applications.

The development of high-strength and intrinsic flame-retardant natural fiber-reinforced green composite (NFRGC) is a landmark for high-performance structural applications. This paper reports a biobased, high-performance, flame-retardant composite material based on diverse bio-resources. Tough and strong cellulose long filaments (CLFs) are combined with vanillin-derived epoxy (VDE) resin to achieve high strength and flame-retardant NFRGC. The green composite was fabricated using a simple hand lay-up and compression molding technique. The green composite showed a noteworthy increment of 100.9 % flexural strength and 346 % flexural modulus compared to the neat VDE resin. Interestingly, despite the highly flammable nature of CLF, the green composite passes a V-0 rating under the UL-94 test, indicating excellent flame-retardant characteristics. Additionally, the green composite demonstrated outstanding hydrophobicity with a water contact angle of 104.2° and good chemical stability in various acidic and organic solvents. The green composite's excellent mechanical and physical properties show its potential for high-strength and flame-retardant structural applications.

High-strength cellulose nanofiber/graphene oxide hybrid filament made by continuous processing and its humidity monitoring.

Human-made natural-fiber-based filaments are attractive for natural fiber-reinforced polymer (NFRP) composites. However, the composites' moisture distribution is critical, and humidity monitoring in the NFRP composites is essential to secure stability and keep their life span. In this research, high strength and humidity sensing filament was developed by blending cellulose nanofiber (CNF) and graphene oxide (GO), wet-spinning, coagulating, and drying, which can overcome the heterogeneous mechanical properties between embedded-type humidity sensors and NFRP composites. The stabilized synthesis process of the CNF-GO hybrid filament demonstrated the maximum Young's modulus of 23.9 GPa and the maximum tensile strength of 439.4 MPa. Furthermore, the achieved properties were successfully transferred to a continuous fabrication process with an additional stretching process. Furthermore, its humidity sensing behavior is shown by resistivity changes in various temperature and humidity levels. Therefore, this hybrid filament has excellent potential for in-situ humidity monitoring by embedding in smart wearable devices, natural fiber-reinforced polymer composites, and environmental sensing devices.