Review on nanocellulose composites and CNFs assembled microfiber toward automotive applications

Abstract

Abstract Nanocellulose derived from plant cell wall, due to its unlimited sources, is regarded as a next-generation green material for the automotive industry because of its high tensile strength (≥3 GPa), high elasticity modulus (110–220 GPa), and low density (1.6 g/cm3). This study first introduces the structural characteristics, preparation techniques, and mechanical properties of nanocellulose. Then, three types of nanocellulose composites, including nanocellulose directly reinforced polymers, hybrid fiber-cellulose composites, and all cellulose composites (ACCs), are reviewed. The corresponding preparation techniques, material properties, reinforcement mechanisms of nanocellulose, and application limitations are discussed in detail. To overcome the insufficient mechanical properties of nanocellulose directly reinforced polymers and ACCs toward the manufacture of automobile structural components, self-assembly techniques prove to be effective to prepare macroscopic fibers by first aligning nanocellulose and then assembling them into continuous micro-size fibers. We reviewed different self-assembly techniques and multiscale modeling techniques of cellulose nanofibers (CNFs) assembled microfibers. Furthermore, we proposed a finite element or finite volume technique-based micromechanics framework to predict the homogenized responses of CNFs assembled microfibers, which serve as a fundamental layer to construct a multiscale modeling strategy toward CNFs assembled microfiber-based composite structures. The proposed multiscale modeling strategy is expected to greatly facilitate the development of CNFs assembled microfiber-based composite structures and significantly advance the application of nanocellulose in automotive structural applications.