The Structure Development of Cellulose Dissolved in the Phosphoric Acid/Polyphosphoric Acid Solvent

Cdlulose,being as the most abundant nature polymer material and the most promising oil substitute,attracts more and more interests.A new cellulose dissolution system,phosphoric acid ( PA)/polyphosphoric acid ( PPA ) solvent,was investigated in this study.It had been found that a larger cellulose solid content could be dissolved quickly in a hypothermic situation.By evaluating the stability of regenerated cellulose film and the formation of anisotropic solution, the dissolution behavior of cellulose was investigated.Wide-angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the crystalline structure and morphology of regenerated cellulose.The measurement results revealed a transition from cellulose- Ⅰ of raw cellulose to cellulose-Ⅱ of regenerated cellulose and a decrease of crystallinity of cellulose after dissolved.This was attributed to the interaction between cellulose and acid solvent,which leaded to the breakage of cdlulose intra- and inter-molecule hydrogen bonds and the conformation change of cellulose C6-OH.Moreover,the formation process of cellulose liquid crystal solution was illustrated by polarized light microscope (PLM).That may be induced by the rearranging movement of the cellulose macromolecular chains.