PREPARATION OF CELLULOSE NANOFIBERS AND ITS APPLICATION IN THE PREPARATION OF NANOCOMPOSITE FILMS

Abstract

Cellulose nanofibers (CNFs) of diameter in the range of 50-100 nm and length upto several micrometers have been prepared by using cherno-mechanical method. Bamboo fibers (BFs) was used as the source and a mild chemical treatment using KOI-! and 1-ICi was carried out. The obtained fibers consists of 94.8% of cellulose as revealed by chemical composition analysis. The pure cellulose fibers obtained were treated mechanically by ball milling and ultrasonication to obtain the nanofibrillated structure. The prepared CNFs were then used as reinforcing agent to make nanocomposite films with polyvinyl alcohol (PVA) by using solvent casting method. To prepare the nanocomposite films the PVA was obtained by hydrolysis of polyvinyl acetate (PVAc) in an alkali medium. Two different approaches have been used to prepare the nanocomposite films. In the first method, the CNFs were added to the already hydrolyzed PVA whereas, in the second method the CNFs was added during the hydrolysis of the PVAc to PVA. Incorporation of only 0.3 wt % CNF to the PVA has improved the tensile strength from 12 MPa in the pure PVA film to 21 MPa (first method) and 60 MPa (second method). Similarly, the Young's modulus for the virgin PVA film was 1086 MPa and it has increased to 2352 and 3752 MPa for the films prepared using the first and second approach, respectively.Thus, the prepared CNFs-PVA nanocomposite films could be used for the applications requiring high strength like packaging and coatings.