Fabrication and characteristics of cellulose nanofibril films from coconut palm petiole prepared by different mechanical processing

- Biodegradabe and renewable cellulose nanofibrils with the diameter of 50-100 nm and the aspect ratio of over 1000 were first time isolated from coconut palm petiole by different mechanical processing.
- Cellulose nanofibril films with the tensile strength of 160.42 MPa, the modulus of 3.64 GPa and the transmittance of 78.1% at 600 nm wavelength had been fabricated without using an organic solvent.
- Providing an approach for more effective utilization of coconut palm petiole as potential feedstock for cellulose nanofibrils.

This paper focused on extraction of cellulose nanofibrils (CNFs) from coconut (Cocos nucifera L.) palm petioles falling off naturally, which if not properly processed constitute an environmental hazard. CNFs were isolated by chemical pretreatments and different mechanical processing, including grinding (G), grinding followed by ultrasonication (GU), and grinding followed by homogenization (GH). As one of the applications of this biodegradable and renewable CNFs, fabrication of films without using an organic solvent has been attempted using the received CNFs. Fourier transform infrared spectroscopy (FTIR) spectra analysis showed that the chemical treatment removed most of hemicellulose and lignin from the palm petioles, remaining only cellulose. SEM observations showed that diameter of the CNFs from GU method was between 50 and 100 nm, and the aspect ratio of CNFs was over 1000. Tensile properties and transmittance of CNFs films with different mechanical treatments were also studied. Compared to grinding treatment, the CNFs film prepared by grinding/ultrasonication and grinding/homogenization treatments presented better tensile properties and transmittance. This work provides a new approach for more effective utilization of coconut palm petiole as potential feedstock for CNFs.