All-cellulose composites with ultra-high mechanical properties prepared through using straw cellulose fiber

All-cellulose composites (ACCs) materials exhibit excellent mechanical properties and attract much attention of researchers. In this work, raw straw cellulose fiber (R-SCF), alkali-treated SCF (N-SCF) and activated SCF (A-SCF) were used to prepare the ACCs, respectively. The results demonstrated that although the three SCFs exhibited similar crystalline structures, i.e. cellulose I, they exhibited different surface morphologies. Morphological characterization about the cryogenically fractured surfaces and the tensile-fractured surfaces of the ACCs, which were prepared through mixing SCF into the microcrystalline cellulose (MCC) solution and then precipitated, clearly demonstrated that the ACCs were a material with a multiphase structure. The mechanical properties of the ACCs were greatly dependent upon the interfacial adhesion between the SCF and the regenerated MCC (RMCC). Ultra-high tensile strength (650.2 MPa) was achieved for the ACCs containing the A-SCF, which was the highest tensile strength reported in the literatures for the isotropic ACCs. The reinforcement mechanism was then analyzed. This work provides new insight on preparing the ACCs with ultrahigh mechanical properties.