Fabrication of nanocelluloses from hemp fibers and their application for the reinforcement of hemp fibers

A novel fabrication has been employed to produce nanocelluloses from natural fibers (hemp) and the developed nanocellulose was then used as “coupling agent” to modify hemp fibers themselves.The size distribution of nano-particles (nanocellulose) was measured by nanoparticle tracking analysis (NTA). Results showed that the oxidation–sonication developed nanocellulose had wider size range (29–281 nm) and the average size (100–112 nm). Morphologies of nanocellulose displayed a slight difference under field emission gun-scanning electron microscopy (FEG-SEM) and atomic force microscopy (AFM). Mechanical testing showed that the nanocellulose modification could improve the mechanical properties of natural fibers significantly. The modulus, tensile stress and tensile strain of nanocellulose modified hemp fibers were increased by 36.13%, 72.80% and 67.89%, respectively. FEG-SEM and X-ray diffractogram (XRD) were used to reveal the mechanism of nanocellulose reinforcement on natural fibers. FEG-SEM illustrated that the nanocellulose treatment had resulted in an effective distribution of nanocellulose along the stria on the surface of fibers, giving rise to a significant increase in the tensile strength of the treated hemp fibers. The XRD analysis also showed that the crystallinity index of the treated fibers had increased from 55.17% to 76.39%. X-ray photoelectron spectroscopy (XPS) has been used to characterize the surface of fibers and attenuated total reflectance-fourier transform infrared (ATR-FTIR) was carried out to determine the surface chemical reaction in order to elucidate the interface properties and self-modification mechanisms of the hemp fibers.

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► Nanocelluloses are fabricated from hemp fibers with oxidation/ultrasonication.
► Nanocellulose modification can increase the mechanical properties and interfacial property of natural fibers significantly.
► We reveal the mechanism of reinforcement of nanocellulose modification by FEG-SEM and XRD.
► We reveal the mechanism of interfacial improvement of nanocellulose modification by XPS and ATR-FTIR.