Material properties of cellulose acetate prepared from celluloses having different molecular weights

We used tunicate cellulose and cotton cellulose as starting materials, and performed acetylation to them with heterogeneous and homogeneous reaction. The obtained cellulose acetates were dissolved in N,JV- dmiethyla ce tamide. and then viscosities and dynamic viscoelastic properties were measured. Cast films were prepared from the dichloromethane solution of the cellulose acetates. Their infrared spectra and visible absorption spectra were collected; and moreover, their contact angle measurements and tensile strength measurements were performed. From these results, we discussed how the characteristics (especially, molecular weight) of the starting celluloses affected the obtained cellulose acetates. The cellulose acetate film prepared with the homogeneous reaction showed higher hydrophobicity and intensity than that prepared with the heterogeneous reaction. In addition, the cellulose acetate film prepared from tunicate cellulose showed higher hydrophobicity and intensity than that prepared from cotton cellulose. It suggests that the hydrophobicity and intensity depend on the molecular weight of cellulose. On the other hand, although the cellulose acetate prepared from tunicate cellulose with the heterogeneous reaction had lower molecular weight, the hydrophobicity and the intensity of its film were larger than the film prepared from cotton origin with the homogeneous reaction having higher molecular weight. It shows the possibility that there is uniqueness that cannot be explained only by a molecular weight of cellulose.