Effect of freeze dry on the properties of cellulose nanofibrils/phenol formaldehyde nanocomposites
In order to decrease the process time and obtain wrinkle-free CNF and CNF-PF composite films, freeze dry were employed in this work to remove the excessive water in wet films. The nanocompsoites were prepared by hot pressing the freeze-dried films. The morphology, main physical and mechanical properties were evaluated. Results show both CNF and CNF-PF composite films exhibit uncontinuous spots, which are considered as voids contributed to low-temperature dry. The films are flexible and strong, though addition of PF has little effect on the increase of mechanical strength. Compared with mechanical strength of films prepared by oven dry, the freeze dry leads to relative decrease of strength. However, when considering the time consumption, freeze dry is an effective way to prepare CNF and its based nanocomposite.