Preparation of Biopolymer Composite Using Cedar-Derived Cellulose Nanofibers

Steam treatment followed by milling treatment, an environmentally friendly method, was used and evaluated as a pretreatment of cedar for the preparation of cellulose nanofiber (CNF). The treated cedar was extracted with water followed by acetone and then received sodium chlorite (NaClO2) treatment, and separated into volatile component, water soluble component, acetone soluble component, NaClO2 soluble component, and NaClO2 insoluble component (a raw material of CNF preparation). The effects of steam pressures on the properties of treated cedar were examined from experimental data for the amounts of extracted components and the degree of polymerization. The properties of CNF obtained from cedar that was steam-treated at a steam pressure of 15 atm for a steaming time of 5 min and then milling-treated for 10 s were almost the same as those of commercial CNF (BiNFi-s). The reinforcing effect of CNF obtained in this treament condition was clarified, and the specific tensile strength and the specific Young's modulus of PLA/CNF composite were 58.1 MPa/g/cm(3) and 7.56 GPa/g/cm(3) that corresponded to 1.6 and 3.1 times higher than those of PLA only, i.e. 33.0 MPa/g/cm(3) and 2.44 GPa/g/cm(3), respectively.