The Effect of Cellulose Nanofibers on the Properties of Starch Biopolymer

The current study deals with the preparation and characterization of polysaccharide-based biocomposite films acquired by the incorporation of cellulose nanofiber within glycerol plasticized matrix formed by starch. The application of starch-based films is restricted owing to highly hydrophilic nature and poor mechanical properties. These problems are solved by forming a nanocomposite of thermoplastic starch (TPS) as matrix and cellulose nanofiber (CNF) as reinforcement. CNF is successfully synthesized from short pure cellulose fibers by a chemo-mechanical process. TPS/CNF composite films are prepared by the polymer solution casting method, and their characterizations are obtained by water vapor transmission rate, differential scanning calorimetry (DSC), atomic force microscopy (AFM), oxygen transmission rate, X-ray diffraction (XRD), light transmittance, and tensile test. Even at the low concentration of CNF filled TPS, the composite film shows improvement in properties. The 0.4 wt% CNF loaded TPS films show approximately the maximum improvement in tensile strength. Above 0.5 wt% CNF, tensile strength starts to deteriorate. Water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) results show improvement in water vapor barrier properties of TPS matrix. The DSC thermograms of TPS and composite films do not show any significant effect on the melting point of the composite film compared with the base polymer TPS. The AFM analysis shows the topography of the surface of the nanocomposite. The morphology of nanofibers is studied by using the scanning electron microscopy (SEM) and the transmission electron microscopy (TEM).