Fabrication and properties of green cellulose nanofibers/polylactic acid composites

This paper reports the preparation for cellulose nanofibers (CNFs) and fabricates CNFs reinforced polylactic acid (PLA) composites with the goal of making sustainable 'green-composites'. CNFs were isolated from wood powder by acid and alkali processing combined with mechanical treatment, containing grinding treatment and high-pressure homogenizing. The nanocomposites were prepared by incorporating 1wt% of the CNFs into the PLA matrix by a dichloromethane solution casting method. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were studied to see the structure of CNFs. The FT-IR indicates that the original molecular structure of cellulose is maintained even after matrix components removal and different mechanical treatments and the SEM images show that the aspect ratio of CNFs is over 1,200. The mechanical properties and the coefficient of thermal expansion (CTE) of the neat PLA and CNFs/PLA composite films were investigated. The results indicate that tensile strength and modulus of PLA are improved and the CTE of PLA is decreased with the addition of CNFs. From the results, CNFs show considerable potential as an effective reinforcement for high quality specialty applications of PLA.