| Abstract:In this study, a cellulose-based porous material was prepared from plant fibers by freeze-drying technique. The effect of the solid content of fiber suspension and freeze-temperature on the microstructure and properties of the prepared porous materials was investigated. Meanwhile, the action and formation mechanisms of ice crystal on the fibers during freezing process and the microstructure of final porous material were discussed. The results revealed that the increase of solid content of fiber suspension could transform the Z direction microstructure of final porous material from an isotropic architecture to an anisotropic lamellar porous structure which could prevent Euler buckling of porous materials, leading to the shortening of plateau curve and the shiftment of densification curve to lower strain percentage in stress-strain curve. With the decreasing of freeze-temperature, the viscous resistance acting on the fibers at the solidification front of ice crystal was enhanced, thus the fibers had uniform distribution as it were swallowed by ice crystal and resulting in the porous materials with less two-sidedness. In addition, porous material produced at lower freeze-temperature owned smaller pores due to the thickness of lamellar ice crystal was reduced, which improved its ability to resist stress and deformation, leading to the densification region in stress-strain curve occurred at lower strain point． |
