OPTICAL AND ELECTROOPTICAL PROPERTIES OF CELLULOSE ESTERS WITH ALIPHATIC SIDE-GROUPS

Cellulose acetate, cellulose butyrate, and cellulose acetate-myristate of various compositions were studied in various solvents using birefr ingence in flow and equilibrium electrostatic birefringence. The optic al anisotropies of macromolecular cellulose esters with aliphatic subs tituents were determined. These anisotropies were found to depend prim arily on the anisotropy of the corresponding aliphatic group, whereas the anisotropy of the cellulose backbone with the attached ester group s is almost zero. The birefringences in flow and in the electrostatic field are found to have the same sign for all of the cellulose esters studied. This indicates that macromolecules experience large-scale reo rientation in both the hydrodynamic and electric fields. The axial com ponent of the dipole moment of the monomer unit of the cellulose ester s with aliphatic side chains is governed by the dipole structure of th eir backbone chain with the attached ester groups.