BioResources (Dec 2011)
STUDY ON THE REACTION OF ALKYL KETENE DIMER (AKD) AND CELLULOSE FIBER
Abstract
A cellulose homogeneous system was prepared by dissolving cellulose fibre in an 8.0 wt% LiCl/DMAc solution. AKD was reacted with the cellulose under the homogeneous system and a heterogeneous system, respectively. The reaction products were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Wide-angle X-ray diffraction (WXRD). The results indicated that hydrogen bonds between cellulose molecules were disrupted under homogeneous conditions. The activity and accessibility to the reagent of hydroxyl groups were enhanced so that the β-keto ester bonds between AKD and cellulose were generated. However, the activity and accessibility of hydroxyl protons of the anhydroglucose units were not highly reactive under heterogeneous conditions. Moreover, cellulose itself was heterogeneous in nature, as different parts of its constituent fibrils displayed very hard accessibilities to the reagent. The β-keto ester bonds were not detected in the reaction products. Thus, the reaction between AKD and cellulose was difficult to achieve under heterogeneous conditions. In the sizing process, the reaction of cellulose should not simply be regarded as being that of a trihydric alcohol that is similar in its chemistry to sugars having three hydroxyl groups. Thus, the controversy about the sizing mechanism of AKD still remains unresolved.
